[in Japanese]

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Three species of dragonets, Callionymus regani, sp.nov., C. gardineri and C. spiniceps, are described from specimens taken from the Saya de Malha Bank in the west-ern Indian Ocean.The latter two are reported as second records with some additional information.

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Coelorinchus kaiyomaru (Gadiformes: Macrouridae) is described from 32 specimens collected off Tasmania and New Zealand.and one specimen from waters off the Falkland Islands.The new species is readily distinguished from other species of Coelorinchus by: the long snout;squamation on head and trunk;absence of a continuous anterolateral edge in the nasal bones (i.e..median and lateral processes not united);a small light organ that lacks a secondary duct;and extent of trunk pigmentation.The new species was previously confused with C. innotabilis McCulloch.1907.

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A new percichthyid fish, Neoscombrops pacificus, is described from Aogashima Island and Okinawa Island, Japan.A neotype for the closely related South African N.annectens is designated to clearly discriminate these two species.The Japanese N.pacificus differs from the South African N.annectens in several characters such as the number of lateral line and transverse scales, and the depth of the caudal peduncle.

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Pronounced geographic variation in meristic characters is found in two Southeast Asian cyprinid species, Puntioplites proctozysron and Puntioplites waandersi.When local populations of each species are combined with other conspecific populations, these two forms overlap in all meristic and morphological characters examined.The only pheno-typically detectable difference between the two is the nature of the principal simple anal ray;the ray is serrated in P. proctozysron and entire in P. waandersi.This difference is shown not to represent individual or sexual dimorphism within a species.P. proctozysron and P. waandersi are considered to be distinct species directly differentiated from a common ancestor belonging to the same genus, Puntioplites, which is distinct from the genus Puntius.
Zoogeographical examination suggests the occurrence of Puntioplites waandersi through-out the continental and insular sections of Southeast Asia in the lower Tertiary or earlier, when these two sections constituted a continuous landmass, and subsequent isolation of continental populations in the middle Mekong basin.The present geographic range of Puntioplites proctozysron, being restricted to the continental section, seems to indicate the derivation of this species in continental Southeast Asia from P. waandersi or a waandersi-like ancestral form.Some aspects of the geohistory of the Indochinese Peninsula are dis-cussed from a zoogeographical viewpoint.

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Effects of grouping on respiration of the medaka Oryzias latipes were investigated using through-flow respirometers and sealed flasks.The oxygen tension of water was measured with polarographic oxygen electrodes.The potential changes accompanying re-spiratory movements were recorded with electrodes of platinum, active and indifferent, in order to determine the ventilatory frequency.The oxygen consumption and the ventilatory frequency of isolated fish in the respirometer tube did not change when the fish were placed in contact through vision alone with their own mirror images, or with others of the same species.The oxygen consumption of isolated fish in the sealed flask was also not affected by visual contact with others of its kind.The oxygen consumption of isolated fish in the sealed flasks slightly decreased when they were placed together in a group of formerly-isolated fish in another flask filled with water which was exactly the same as the total volume of water used for each isolated fish.However, the decrease was too slight to suggest that the metabolic rate of isolated fish is influenced by the changes in visual con-ditions and by direct contact with others of its kind.

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By using the Golgi impregnation methcd in the study of lamprey hypothalamus, it is demonstrated that the nucleus preopticus consists mainly of neurosecretory neurons similar to the type of CSF-contacting neurons.A small number of horizontal cells are also detected in this area.In addition to these cells another type of CSF-contacting neurons are seen in the ventral part of the nucleus preopticus.While both nucleus hypothalami dorsalis and nucleus hypothalami ventralis situated in the posterior part of the hypothalamus are occupied exclusively by the CSF-contacting neurons bearing the ventricular process, the nucleus recessus posterioris hypothalami in this area are found to have the neurons equipped with processes bearing varicosities that are projected toward the ventricular surface.Ten to 12 hours after the administration of HRP that is retrogradly transported in axon from the hypophysis, this agent appeared in several sites, such as the CSF-con-tacting neurons of the nucleus hypothalami ventralis and nucleus hypothalami dorsalis, both just above the pars nervosa, as well as neurosecretory neurons of the nucleus pre-opticus.These results may intimate that the pars nervosa of the lamprey hypophysis is innervated from the monoaminergic CSF-contacting neurons located in the lateral wall of the third ventricle, in addition to the neurosecretory nerve fibers.

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[in Japanese]

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