ON THE APPENDICES GENITALES [CLASPERS) IX THE SELACHIANS. 51 



The exterior of the appendix is chiefly as in Torpedo; we find here the same marginal slits 

 (and pockets I, but the medial one is with the buttonhole shaped, distal part situated quite on the 

 dorsal side, and the lateral one is turned a little ventrally; next it is to be 

 remarked that the appendix-slit in the whole of the free part of the organ is 

 King quite laterally, the dorsal lip overlapping it quite to the outer edge 

 like a cover, much broader than in Torpedo; corresponding to this the portion 

 of the terminal part containing the piece Td is folded quite over the hindmost -I — b,i 



part of the appendix-slit. The glandular bag and its inner gland are relatively * A i 



more strongly developed than in Torpedo. 



Td 



In the skeleton, notwithstanding the principal conformity with. Torpedo] 



several peculiar features are found. Between the basale and the appendix- 



Narcine sp. The right 

 stem also here two pieces, b t and o 2 , are found, the former short, the latter appendage from the 



longer; b x bears the last rav at the connection with the basale; the last ray dorsal side. Natural 



size. / the opening of 

 but one seems to me only to articulate with the basale. The piece /? is to- the medial pocket. Rd, 



tallv wan tin?;. The appendix-stem is long- considerably longer than the ba- s-eea par co- 



& l r & ' . & vered by the skm. 



sale -|- b Y and b 2 ; it is calcified in the surface excepting the short end-style, 



which distally becomes broad, flat, with rounded hindmost contour. The marginal cartilages are thin, 

 rather short, and occupy only the hindmost half of the stem; the ventral one shows the same features 

 as in Torpedo ; also here it reaches a little farther forward; the dorsal one, when seen from the dorsal 

 side, forms a broad, ovate leaf tapering proximally, and continuing as an uncalcified band quite to 

 the articulation of the appendix-stem with b 2 ; its lateral edge reaches to the free edge of the ventral 

 marginal cartilage; seen from the ventral side it is hollowed in a trough-like manner as in Torpedo; 

 but distally it does not nearly reach so far as in the latter, and consequently the two marginal car- 

 tilages do not end so obliquely of each other distally (this fact seems also to imply a greater mobility 

 of the terminal part in Narcine than in Torpedo). 



The number of terminal pieces is three, to which is to be counted a quite similar ventral 

 covering piece v as that in Torpedo. As already mentioned, Td is folded to the dorsal side, and has 

 apparently a shape deviating considerably from that found in Torpedo; a closer examination shows 

 however that this deviation to some degree is due to the position; on the medial-dorsal side the piece 

 is hollowed in a groove-like manner (for the medial * marginal slit ■■); otherwise it is flatly rounded 

 on the outer surface, concave towards the appendix-slit, with a sharp lateral, convex edge. 



Tv is short, oval, rounded towards the appendix-slit (as in Torpedo) concave on its outer sur- 

 face, by which, together with the covering piece z», it forms the hollow for the lateral «pocket». T~ 

 is somewhat s-shaped, tapering to both ends, little and slender. The covering piece is chiefly as in 

 Torpedo; also here we find on both its margins curvatures destined (especially on the lateral margin) 

 to form the button-hole shaped opening of the pockets together with the terminal pieces Td and Tv. 

 The foremost lateral corner appears independent as a very small v'. 



The muscular system is as in Torpedo with the exception that the part of the M. com- 

 pressor that may be seen on the ventral side, is relatively larger, and laterally spreads somewhat 



