余ハOddi氏筋ノ研究ヲ主眠トシ此筋ノ有無乃至其強弱如何ハ之ニ連絡スル膽道即チ肝管、膽嚢、膽嚢管、總輸膽管等ニ直接間接ニ大關係ヲ有スルヲ以〓此等諸機管ノ比較解剖學的及ビ比較組織學的研究ヲ系統的ニナサントシ脊推動物ノ最モ低級ナル圓口類ヲ初メトシ魚類、兩棲類、爬虫類、鳥類及ビ哺乳類ニ就テ續行スルコトトセリ。
茲ニ第一同報告トシテ圓口類二種及ビ魚類十五種ニ就テ報告スルコトトセリ。(自抄)

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Rokuro Nagasawa was a student in University of Tokyo under Professor Isao Ijima. He was involved in editing a zoological magazine named “Dobutsugaku Zasshi”, then the official journal of the Zoological Society of Tokyo, but his subsequent life is not well documented. We conducted bibliographic surveys to evaluate Nagasawa’s achievements. He entered the University of Tokyo in 1907 and was in charge of editing “Dobutsugaku Zasshi” from 1911 to 1917. After that, he suddenly disappeared from the Zoological Society of Tokyo and moved to Vancouver, where he worked as an editor-in-chief of Japanese newspapers. He wrote many newspaper articles under the pen name of “Nanbokusei”. Prior to moving to Canada, he also wrote under the pen name of “N.S. Sei”. He returned to Japan before World War II, and worked as a high school teacher in Kyoto. He then moved to Hyogo prefecture and wrote and edited the local history of the area.

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In this note the present author has annotated on twelve unrecorded species of fishes with brief descriptions, to be included into the ichthyofauna of Echigo and Sado, Japan, and two species which are thought to be omitted from the ichthyofauna of this region.
1. Among the fishes to be added herein, there are two kinds of remarkable and rare subtropical fishes, which are young Diproprion bifasciatus and medium sized Therapon theraps. It should be mentionel that Sado and its neighbouring region are northern limit for their occurrence. The counts and measurements of the specimens of these two species are as follows: -
(1) Diploprion bifasciatus KUHR et VAN HASSELT
Total length 39.8mm, body length 30.5. Head 2.5 in body length; depth 2.3; snout 2.7 in head; eye 3.6. D. VIII, 15; V I, 5 and A II, 12. Second and third dorsal spines remarkably filamentous, whose length 38 and 63mm as measured to tip of filament respectively. Body strongly compressed laterally, color generally yellowish white (Fig.1).
(2) Therapon theraps CUVIER et VALENCIENNES
Total length 132, body length 108. Head 3.2 in body length; depth 2.3; snout 3.5 in head; eye 3.6. D. XII, 10; V. I, 5 and A. III, 8; with a strong opercular spine. Four straight longitudinal dark bands running lateral body, and a blackish blotch lying from third to seventh dorsal spines. Lower jaw protrude somewhat beyond upper jaw. This species is unrecorded form from the western coast of Honshu, Japan Sea (Fig.2).
2. Two rare boreal or deep-sea fishes of central Japan, which are referable to the families Cottidae and Zoarcidae respectively, were found in the Sado Channel. These were reported as new species from Toyama Bay by MATSUBARA (formerly SAKAMOTO) and KATAYAMA respectively. They are: -
(1) Marukawichthys amburator SAKAMOTO, 1931
Two specimens, body length about 160, collected by the Japan Sea Regional Fisheries Research Laboratory.
(2) Petroschmidtia toyamensis KATAYAMA, 1941
One specimen, total length 313, collected by the Japan Sea Regional Fisheries Research Laboratory.
3. A scorpaenoid fish, Sebastes matsubarai HILGENDORF and an ophidioid fish, Lycogramma zesta (JORDAN et FOWLER) are thought to be excluded from his former list.

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There are four species of Eleotris found in Japan: E. oxycsephala TEMMINCK & SCHLEGEL, E. melanosoma BLEEKER, E. acanthopomus BLEEKER and E. fusca BLOCH & SCHNEIDER. Specimens of these four species and E. mauritianus BENNETT and E. sandwicensis VAILLANT & SALTVAGE which resemble them were compared in detail. The specimens counted and observed in this study are listed in table 1. Besides these, BLEEKER'S specimens from Rijksmuseum van Natuurli jke Historie were examined, and they are listed in table 14 with the results of the observation dealt with separately from the results of the observation in this study.
The fin counts and the characteristics of scales which show certain degrees of difference are shown in tables 2-9.
The characteristics of the gill rakers are clearly distinguishable among the species. The shapes of the outer gill rakers on the 1st arch of E. oxycephala are very distinct, being short pedestals covered with spines (fig. 14), while the outer gill rakers of others are rods with spines on their inner side (fig. 15). The number of outer gill rakers, the ratio between the length of the portion without gill rakers in the ceratobranchial against its length and the position of outer gill rakers in relation to inner gill rakers are different among the species (figs. 16-17, table 10-12). Together with these, the sizes of the membranes between the 1st gill arch and the pharynx are also different among them (figs. 18-21). The difference between E. melanosoma and E. acanthopomus which is not distinguishable on the scale counts is very conspicuous here. The patterns of pit organs on the head are the most distinguishable characteristics (figs. 1-12 and 22-25). The pit organs of E. oxycephala are very different from those of other species, having longitudinal rows of pit organs from the chin to the lower margin of the preopercle (fig. 9), instead of having transverse lines (fig. 10). And also E. oxycephala has a longitudinal line of pit organs immediately behind the eye (line 13 in fig. 5), instead of a transverse line (line 8 in figs. 6 and 7, and line 10 in fig. 8). E. melanosoma differs from the others in having more prominent lines of pit organs (fig. 23). The characteristic patterns of pit organs in the infraocular region of each species are shown in figures 5-8. In E. oxycephala, lines 3, 4 and 5 do not cross line 11 (fig. 5); in E. melanosoma, only line 5 does not cross line 13 (fig. 6); in E. acanthopomus, E. mauritianus and E. sandwicensis line 3 and 5 do not cross line 13 (fig. 7); in E.. fusca lines 3, 5 and 7 do not cross line 15 (fig. 8). Anomalous arrangements of pit organs are not found on both sides of any specimen examined except on a specimen of E. fusca which has seven lines instead of eight. The transverse lines of pit organs along the preopercle differ, too, among the species as shown in table 13. Pit organs on the opercle are of two types (figs. 11-12): the one in which line 1 and line 2 do, not meet is that of E. oxycephala, E. acanthopmus, E. mauritianus and E. sandwicensis; the other in which line 1 and line 2 meet and line 2 does not cross line 1 is that of E. melanosoma and E. fusca. The anal papilla of the female of E. oxycephala is also different from that of the others in that it has fringes on the posteriormargin (fig. 26), while the others have no fringes (fig. 27). E. oxycephala is different from the others in coloration, too, having two dark lines backward and downward from the eye, while the others have three, although it is often difficult to observe these lines. In most of the specimens of E. melanosoma these lines could not be seen. The clear difference in the characteristics of gill rakers and pit organs separating E. mauritianus and E. sandwicensis

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Eight specimens (28.2–170.2 mm SL) of the non-indigenous bagrid catfish Pseudobagrus fulvidraco were collected from the Lake Kasumigaura system, Ibaraki Prefecture, central Japan, during December 2008 and November 2011. Three juvenile specimens of this invasive species indicated successful reproductive activity in the lake system. The species is known to have similar morphological and food habits to channel catfish Ictalurus punctatus, which has also invaded Lake Kasumiguara, causing damage to the ecosystem and problems for local fisheries. The establishment and future habitat expansion of P. fulvidraco would also cause serious ecological and economic problems.

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Phylogenetic relationships among 4 major geographic population groups (San-in-Biwa-Ise, East Seto, West Seto and West Kyushu) of Japanese freshwater goby Odontobutis obscura (Perciformes: Gobioidei: Odontobutidae) and related species O. hikimius were inferred from partial nucleotide sequences of the mitochondrial 12S and 16S rRNA genes. The resultant mitochondrial DNA (mtDNA) phylogeny was consistent with that based on the previous allozyme analysis. This phylogeny showed that specimens from the Sagami River system in Kanagawa Prefecture, Kanto District, were extremely close to fish from the West Seto group, suggesting the formers to have been descended from individuals artifi-cially introduced from the range of the latters. Judging from the fact that about 40 individuals of the goby were easily collected by a person in 2 hrs, the Kanto popu-lation did not seem to be small, and thus might be disturbing the native fauna in the river system.

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The genus Sicydium was established by Valenciennes (1837) with Gobius plumieri Bloch as its type species. Sicyopterus was first established by Gill (1861) as a subgenus of the genus Sicydium with Sicydium stimpsoni Gill as its type species, and later raised to a generic level by Bleeker (1874).Since then the two generic names, Sicydium and Sicyopterus have been used for the type species of the genus Sicyopterus.
Sicydium and Sicyopterus were insufficiently diagnosed by Gill (1861), Bleeker (1874 and 1876).and Koumans (1931), so that the characteristics given by them do not agree.
Our comprehensive study of the type species of the two genera, Sicydium cocoensis (Heller et Snodgrass), Sicyopterus japonicus (Tanaka), Sicyopterus macrostetholepis (Bleeker), Sicyopterus parvei (Bleeker), and Sicyopterus pugnans (Grant) revealed that the characteristic differences of these species are divided into three levels as follows.The two species of the genus Sicydium and the five species of the genus Sicyopterus are distinguishable at level I.The characteristic differences between them are shown as A and B in Table 3.At level II on the one hand the two species of the genus Sicydium are distinguishable in that their characteristic differences are the presence or absence of a median cleft in the upper lip, of a fleshy tubercle behind the cleft, of the middle pore N of the preopercular canal, and of the ctenoid scales, which are expressed as C and D in Table 2.On the other hand Sicyopterus pugnans and the four other species of the genus Sicyopterus are distinguishable by the presence or absence of a median cleft in the upper lip, of the projections lining the edge of the upper lip, of a fleshy tubercle behind the cleft, of the ridge with protuberances inside the upper lip, by the tips of the teeth in the upper jaw being divided into two or three, by the presence or absence of the flapped lateral lower lip, and by the row of labial teeth being extended or not beyond the last tooth of the upper jaw, which are expressed as E and F in Table 2.At level III the four species of the genus Sicyopterus are distinguishable by the widely or closely set papillae between the band of papillae on the lower lip and the labial teeth, and the differences of fin ray and scale counts, which are expressed as G, H, I, and J in Table 2.Since the differences at level I are sufficiently remarkable to be of generic level, the genus Sicyopterus should be separated from the genus Sicydium, so that A and B in Table 3 become the diagnostic characters of the two genera.However, some of the characteristic differences shown in Table 3 might have to be omitted when more species of the two genera are examined.

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東アジア原産のコウライギギTachysurus fulvidraco は2008 年に日本で初めて発見され， 2016 年に特定外来生物に指定された．本種による生態系や社会経済への影響が懸念されているが，その実態はいまだ明らかではない．そこで，本種の侵入が確認された印旛沼を対象に，その生息状況と水産業への影響について調査した．本研究では2018 年5 月から12 月に採捕された試料の生殖腺指数や体サイズの変動から，繁殖期が少なくとも5 月から7 月頃であると推定された．さらに漁業で混獲される個体の多くは，食品への混入リスクが高い当歳魚であることがわかった．また本種による水産業への被害の有無を明らかにするため，アンケート調査を行った．その結果，本種の鋭い棘条によって漁業者や水産加工業者が怪我をするほか，加工原料となる小魚に混入し仕分け作業が増加するといった被害が明らかになった．

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