2G0 bulletin: museum of comparative zoology. 



The Brain, Plates 14, 15. 



The brain of recent Chimaeroids is crowded together posteriorly. The 

 optic and inferior lobes are close to the medulla oblongata and are below the 

 cerebellum. The hemispheres are remote from the optic and inferior lobes, 

 and the connections with them are slender and nerve-like. This shape of the 

 brain, the massing that has taken place backward with the remoteness that 

 obtains forward, is characteristic of the group, so far as known living genera 

 are concerned. A similar crowding of parts of the brain is common among 

 Plagiostomes, but the wide separation of the hemispheres from the o]3tic lobes 

 is peculiar to Chimaeroids. In some genera of the latter the olfactory bulbs are 

 distant from the hemispheres, so also in particular Plagiostomia, but in one 

 genus each hemisphere is closely connected with an olfactory bulb. In these 

 cases either remoteness or the absence of separation of the olfactories serves 

 to distinjiuish the frenera. 



The brain of Rhinochimaera pacifica, Plate 14, from the medulla oblongata 

 forward to the optic lobes differs comparatively little from that of its allies. 

 The posterior mass is similar in shape and in the positions of its component 

 parts. Compared with Chimaera colliei, Plate 15, Figures 1 and 2, or Callo- 

 rhynchus milii, Figures 4 and 5 of the same plate, the l)rain of the present 

 specimen is somewhat smaller in the cerebellum, which does not cover the 

 optic lobes so completely as in the other cases ; this deficiency in size, however, 

 may be a feature of the individual and not a character of the species. The 

 nerve-like connections with the hemispheres are more slender in Rhinochimaera 

 than is the case in the other genera. In the distance between hemispheres 

 and olfactory bulbs Rhinochimaera pacifica agrees with Callorhynchus milii, 

 Plate 15, Figures 4 and 5, though the connections are even more slender than 

 in the latter species and the olfactory bulbs are smaller. Between the hemi- 

 spheres and the olfactory bulbs in Rhinochimaera the distance is about twice 

 that between the hemispheres and the optic lobes ; in Chimaera colliei the dis- 

 tance between olfactories and hemispheres has vanished, while that between 

 the latter and the optic lobes remains. Similar comparisons may be made with 

 the brain of Chimaera monstrosa, which has been worked out by Dr. Wilder 

 and others. 



Miscellaneous. 



The first mention of the species described above, and a full-grown male of 

 which is figured on Plate 1, in one-third of its life size, was ])ublished by Pro- 

 fessor K. Mitsukuri in the Tokyo " Zoological Magazine," No. 80, Vol. VII., 

 June, 1895, with an outline sketch on Plate IG of the same volume. The more 

 important portion of this notice, containing all the description, is reprinted 

 below. By some mistake the outlines were said to be those of a male ; they 

 are evidentlv those of a female. Professor Mitsukuri's remarks are given in 

 Lis own words : — 



