THE EGG-CAPSULE. 



37 



21 



22 



Fig. 21. Egg-capsule of Chimaera phan- 



tasma. Misaki, Japan. (Ventral aspect.} 



Natural size. 

 Fig. 22. Egg-capsule of Chimaera mit- 



sukurii. Misaki, Japan. (Ventral aspect.) 



Natural size. 



blance to Rhinochimsera it evidently 

 belonged to a similar fish. It is thus to 

 be attributed, with strong probability, to 

 the only Chimseroid of this character 

 known from the region in which it was 

 taken, i. e., Harriotta.* 



A second capsule (fig. 20), hitherto 

 associated with Callorhynchus, should 

 provisionally be placed with the present 

 genus. Although collected in the Indian 

 ocean, it .resembles closely the capsule 

 from the Atlantic, having the same type 

 of lateral web, costae, and subterminal 

 opercular margin, f 



Rhinochimaera. 



Capsule with case spindle-shaped; snout-sheath 

 stouter and thicker than tail-sheath; lateral web 

 wide, its outer margin transparent, strengthened 

 by a regular series of tapering costse. Lip of 

 dorsal valve ends in a narrow, delicate lip, sub- 

 terminal. Serrulse low and faint. No dorsal keel; 

 in its place a shallow groove extends along the 

 dorsal wall of the caudal sheath. Caudal pores 

 similar to those in Harriotta (?). Capsules 

 smooth, dark-colored, hornlike. 



The capsule shown in fig. 23 has been 

 definitely associated with the species 

 R. pacifica. It differs notably from 

 the Indian capsule in proportions, in the 

 number and character of its costae, and 

 in its operculum. 



On the foregoing pages the egg-cap- 

 sules of Chimgeroids have been referred 

 to in considerable detail, since by a com- 

 parison of their characters light is thrown 

 upon the problem of Chimseroid descent. 

 For it is clear that the different species 

 of Chimasroids produce capsules specific- 

 ally distinct; and it follows, therefore, 

 in the light of evolutional analogies, that 

 the fishes which produced the more 

 differentiated capsules are the descend- 

 ants of those in which simpler capsular 

 structures prevailed. It follows, also, 

 conversely, that the forms which have 

 the simpler capsules are apt, in this and 

 other regards, to represent more closely 

 the common ancestor. This evidence, 



* Harriotta has been taken between lat. 36 and 40, long. 70 and 75; from greater depth, however 700 to 1,100 



fathoms. The latter difference is not all-important, as by many analogies spawning might well occur at a lesser depth. 



fThe writer recently examined this specimen in the Calcutta museum, through the courtesy of Major Alcock. 



