96(5 MKS. O. A. MERRITT IIAAVKES OX THE [J)lC. 11, 



ap^iearaiice of secreting cells. Each tubule ends in a group of 

 ainjiullaiy pouches, which are joined with those of the other 

 tubules into a compact nuiss. Unfortunately, it has not been 

 possible to determine cei'tainly whether the lumen in the pouch- 

 region of each tubule remains distinct, or whether the lumina of 

 this i-egion of the tubules communicate. On the whole, the 

 evidence indicates the former. 



It is impossible to state the exact homology of these ampullse 

 with those such as are found in, say, Lcemargus, as the develop- 

 ment of both is unknown. But, judging from the work of Coggi, 

 it seems possible that each compound group of ampnllje in C/da- 

 mydoselachus and in Ghimcera is produced by what Coggi 

 (2. p. 295) calls the " stadio di ampolla individualizzata," whilst 

 L(i'inarguH-\\k.e, tubules are each produced by tlie direct develop- 

 ment of one of the above " ampolla, individualizzata." Hence, 

 fi'om the embiyological point of view, each gi-oup of compound 

 ampulla? in Chlavn/dosehic/uts may be I'egarded as the homologue 

 of a single ampullary tiibule such as is found in Lcemargus, (fee. 



D, The Eye, Eye-muscles, and ISTerves. 



The e^^e is deeply seated in a socket, the external outline of 

 which has the shape of a biconvex lens. Thei-e are both upper and 

 lower eyelids, bixt no nictitating membrane. The infolding of 

 the skin in both cases is sudden and distinct, that of the lower 

 lid is remarkable for its depth, extending almost to the liack of 

 the eye. The infolded membrane both above and below the eye 

 is deeply pigmented, the lower being also provided Avith fine 

 scales. This pigmentation, which on the under side of the eye 

 is as deep as tliat of the surface of the body, together Avith the 

 presence of scales, indicates that the infolded portions become, 

 at times (that is Avhen the eye is protruded), a part of the super- 

 ficial skin. Those portions of the inner surface of the eyelids 

 Avhich are never evaginated are quite smooth and of a light colour. 

 The eye can easily be proti'uded, and when in this position does 

 not look outAvards but upAvards, a position made possible by the 

 large conjunctival fornix. It is known that Chlami/doselachiis is a 

 deep-sea fish, in Avhich case an eye Avhich could look upwards 

 Avould be of the greatest advantage. This protrusible eye no 

 doubt also explains the mai'ked cephalad position of the optic 

 nei'A^e, Avhich is thus placed because the movement is not only 

 iipAvards but slightly antei'ior. 



To keep the eye Avell out in the socket there is an ojitic stalk 

 or I'od of cartilage, common amongst Elasmobranchs (12. p. 25), 

 Avhich also serves here as a base of origin for the recti muscles. 

 The eye-stalk is someAvhat more than 1 cm. in length and 

 about 3 mm. in diameter. It is attached to the side of the 

 cranium, near the base, just in front of the trigemino-facialis 

 foi'amen. The stalk is directed forwards in a curA'ed line and 

 ends in a, flattened, enlarged knob Avhich is applied to the inner 



