THE EGG-CAPSULE. 



31 



CLASSIFICATION OF CAPSULES. 



Fig. 14. — Egg-capsule of fossil Cliimaeioid, Ischyodus(Aletodus). 

 from Dogger beds (Jurassic), Germany. After Jaekel. Actual 



From the materials provided in the 

 present table and figures the egg-capsules 

 of Chimseroids may be classified on some- 

 what the following basis : 



Callorhynchus. (Fig. 15 a-f.) 



Capsules with case spindle-shaped; snout-sheath 

 subequal in length to the tail-sheath; lateral web 

 broad, exhibiting stout rugje; of these a conspicu- 

 ous pair proceeds outward from hinge of opercular 

 valve. No serrulse present, the opercular ridges 

 merely separating to admit water, as in related 

 structures in sharks. No caudal pores; in their 

 place a slit on each side of tail-sheath opening on 

 the ventral side in the angle between web and case. 

 -Anterior lip of operculum transverse, situated on 

 dorsal side at a considerable distance from anterior 

 margin of capsule. No dorsal keel. Heavy cap- 

 sules, leathery and glabrous. 



No capsules of Callorhynchus are 

 known to be definitely associated with par- 

 ticular species, although many of the speci- 

 mens preserved in museums are ascribed 

 to " C. antarcticus." From a study of 

 the capsules of the species of Chimaera, * 

 however, it is clear that the differences 

 between the capsules described are such 

 that we can not believe that they belonged 

 to the same species. Thus the Chilean 

 capsule (fig. 15), described by Jaekel as 

 "Gr/. antarctiats" (a synonym of C. cal- 

 lorhyncluts of Valenciennes) is probably of 

 a different species from the similar egg- 

 case (fig. 1 5 a) figured by Dumeril, and 

 this in turn is notably different from sev- 

 eral specimens in the zoological museum of 

 the Jardin des Plantes, which the writer 

 was recently permitted to examine through 

 the courtes}' of Professor Vaillant. The 

 latter capsules are accordingly figured 



* Variation of the capsules within the range of the species was studied by the writer in the instance of Chinucta 

 coUiei. About eighty capsules were examined, but the variations were found different in character from those 

 referred to in the present pages. 



