A new locality is found from Japan on the crab, Lithodes aequispina Benedict (1894). This crab has been taken from waters, 450〜740m in depth, off Shioyazaki, Fukushima Prefecture. The crab in question is characterized by the rostrum, which is armed with 9 (Fig. 1B) or 10 spines. Sometimes 3 spines are found on the dorsal surface of the rostrum, when the spines of the rostrum enumerate 10 spines in total number. The carapace furnished with 111〜161 acute short spines (Fig. 1A). This spines have a trend decreasing in number with growth. An individual, 85mm in carapace length, bears 161 spines, that, 112mm long, has 136 spines, and that, 160mm long, has 111 ones. In adult form, the width of the carapace is larger than the length of the carapace. This inclination seems to be a little more salient in male than in female as shown in the Table 1. The egg of this crab is comparatively lager, measuring ca. 1.1mm in longer diameter, ca. 0.9mm in shorter one. Fishery of this crab, in Iwaki city, Fukushima Pref., takes place during the months from December to September. Vigorous season ranges from January to March. Some females taken in March are found bearing eggs beneath abdomen. This crab is fished by using a cage about 45cm and 120cm in diameter of the mouth and the bottom respectively, about 58cm in height. Some fishes, such as scomber, saury, sardine, anchovy, and others are used for the bait.

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Previously the author described four species of Cumacea from the Japanese southern coast of the Sea of Japan as new to science: Leucon simanensis (Gamo, 1962), which was obtained from the materials of cumaceans collected by Dr. TAIJI KIKUCHI of the Amakusa Marine Biological Station of the Kyusyu University during his ecological survey of Shinji Lake and Nakanoumi Lake in Tottori Prefecture, and Bodotria biplicata, Pseudoleucon japonicus, and Schizotrema sakaii (Gamo, 1964), which were found in the collection made by the author at Sado Island from 22 to 28 October 1962. The present short report deals with the further result of the examination of the samples of the two collections. [table]

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The author reviewed his former studies on the minute structures of fossils in Japan. Minute structures of carapace in some recent and fossil crabs are investigated in this paper, based upon the photographs of electron-microscope. Carcinoplax longimanus-the recent species shows the horizontal and inclined structures in the section of carapace, in which a canal system may be found. The diameter of the canals is ranging from 1 to 3 microns. Cancer minutoserratus from the Tatsunokuchi formation in Sendai shows the assemblages of polygons with linear structure, in the surface of carapace. Carcinoplax prisca from the Miocene formation of Miyazaki Prefecture shows sub-rounded polygonal assemblages on the surface of the carapace. Notopocorystes stokesii from the Cretaceous Greensand of Cambridge shows rounded polygonal assemblages on the surface of carapace. It seems that fossil crabs have the tendency of orthogenetic evolution from the rounded polygonal assemblages in the minute structure of the surface of carapace to the angular ones, but the mutual relation of the minute structure of carapace in the recent species between the surface and the section is not yet clear. In future, it is most necessary to observe the sections of carapace of fossil crabs by electron microscope, and subsequently to study the relation between micro-structures of inorganic materials of carapace and organic materials in fossil crabs.

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[in Japanese]

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This paper deals with the sacculinization occurred in a male of the pea crab, Pinnetheres sinensis Shen. The specimen was found living commensally within the mantle cavity of the common bivalved shell, Mytilus edulis Linne, obtained on the coast of Tokyo Bay in October, 1964. The body of the adult normal male of Pinnotheres sinensis is rather flat and solid, much smaller than the normal female which has the grobular and soft-shelled body. Even in the largest male, the length of carapace is less than one half that of the fully grown female. In the male, the chela is somewhat thickset compared with that of the female and its propodus furnished with 10-13 setae near the distal end of the anterior border. In second and third pairs of the male ambulatory legs, the carapus is crossed by an oblique row of long feathered hairs, and the propodus fringed with same hairs along the anterior borders. The dactylus of all pairs is claw-shaped and shorter than the propodus. In the female, the dactylus of the last ambulatory leg is rod-shaped and longer than the propodus, furnished with longish hairs along the inner border, with short hairs around the whole surface in distal half. The width of the male abdomen is much narrower than that of the female-about one fifth the length of the carapace, and its sixth abdominal segment has a hook-shaped process on the lateral margin. Of the two pairs of male pleopods, the posterior one has a short flatty exopodite. Of the four pairs of female pleopods, the posterior two are uniramous and has no exopodite (Fig. 1). The external morphological modifications are seen in the male, by sacculinization, as shown in the following: a) The size of the body becomes comparatively larger than in the normal male, and its exoskeleton becomes softend as in the female body (P1. VI). B) The chela becomes somewhat slender and the setae on the propodus are replaced by soft longish hairs, covering the distal surface of both fingers (Fig. 2, 3). C) The long feathered hairs seen on the second and third ambulatory legs are worn out and the dactylus of the fourth ambulatory leg is longer than the propodus, furnished with long hairs as seen in the female (Fig. 2, 1). D) The width of abdomen is broadened; the lateral margin of the sixth segment becomes entire and with marginal hairs (Fig. 3). E) No change of form seems to occur in the first pleopod except for its tip. The carified bridge at the foot of the first pleopod is rudimented. The exopodite of the second pleopod is well developed and covered with long soft hairs. No pleopod is seen in the third abdominal segment, while in the fourth abdominal segment, a uniramous appendage is seen on the right side (Fig. 3 and 4). The internal morphological modifications are seen in testis and midgut gland. These organs are entirely rudimented, being only represented by withered cells. The roots of the parasite glowing thickly around the vas deferens, the midgut gland, the anterior portion of intestine, and the thoracic ganglion. In vas deferens, however, sperms and spermatophores are still seen filling the duct. The penetration of roots of the parasite into the thoracic ganglion has already been investigated by the previous authors (MATSUMOTO K. (1952) and HOSHINO K. (1962)), so the author's present investigation is confined to that of the vas deferens.

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Two megalopa larvae of Percnon planissimum (Herbst) were obtained on the coasts of Hayama, Sagami Bay (Sep., 1964) and Hachijo Island (Aug., 1966), and reared in the aquarium until they reach the first crab stage. Megalopa stage: (The carapace 5mm in length, 3.8mm in width.) The carapace has no dorsal spine. The dorsal surface of carapace is thickly covered with a fine tomentum. The rostrum is horizontally projecting forwards. The postero-lateral portion of the carapace is somewhat swollen. The flagellum of second antenna has ten segments and its distal segment is furnished with a short hair and two long ones. In the third maxilliped the endopodite has the distal five segments setose and its exopodite one-segmeted and about half as long as the ishium. The dactylus of the fourth ambulatory legs is provided with two long feelers at the distal end. The second to fifth abdominal segments are respectively provided with a pair of biramous pleopods. There are 33〜44 swimming hairs on the lateral margin of the exopodite of pleopods. The small hooks are growing along the inner margin of the endopodite of pleopods. The sixth abdominal segment is provided with a pair of uropods, which are rather smaller in size, bearing 25〜26 swimming hairs on the lateral margin. The number of segments of exopodite and that of swimming hairs are compared with those of the megalopa of Plagusia dentipes and Plagusia depressa tuberculata in Table I. First crab-stage: (The carapace 5.5mm in length, 5mm in width.) The aspect of the body approaches that of the adult crab. The carapace is slightly larger than that of the megalopa. In the first crab-stage, the abdomen has seven distinct segments, while in the next stage (carapace 8mm in length, and 8mm in width), the third to fifth abdominal segments are almost coalescent with each other as in the adult crab.

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1. The present paper deals with the carcinological fauna of the Izu-Ohshima and adjacent islands (shown in text-figures 1〜2) during the years 1954〜1965. 2. The specimens of crabs hitherto idetified number 130 species referable to 78 genera and 16 families as shown in table 1. Biogeographycally, the authors divided these specieis into 7 routes, after the view of Sakai (1940, 1. C.). [table] 3. The new northern limit of the tropical species number 22, including three noteworthy species, which have hitherto been recorded from distant southern localities such as Bonin Island, Northern Daitojima and Loo Choo. 4. The features of the fauna of these islands generally resembling those of the southern Japan; some species to have extended from the Hachijo Island, but the most show more tropical or subtropical aspects than in the adjacent districts of the Japanese mainlands. 5. Izu-Ohshima is a volcanic island and is surrounded by rock beaches but we could obtain 3 species of the sand crab--Ocypoda stimpsoni, O. cordimana and Scopimera globosa; no typical esturine areas, but could obtain Eriocheir japonicus and Sesarma (Holometopus) haematocheir; and only a few fresh water streams but Potamon (Geothelphusa) dehaani is not uncommon. 6. Seven species enumerated below are rare in Japanese carcinological fauna, -Lasiodromia coppingeri unidentata, Achaeopsis rostrata, Platymaja myville-thomsoni, Ovalipes iridescens, Charybdis orientaris, Lybia tessellata and Geograpsus crinipes.

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