42 



ON THE APPENDICES GENITALES (CLASPERS) IN THE SELACHIANS. 



Fig. 1.^. 



II, 5'^'" (from the foremost edge of the pelvis to the hindmost jDoint of the appendix the length is 

 24*="")'); the largest breadth is found somewhat above the hindmost point of the fin-membrane, and is 



about 3,5'^'". The ventral side is flat, 

 covered with dermal teeth till the 

 naked terminal part (4,3"" long, 

 2,1'^'" at the broadest spot, at the 

 base); these dermal teeth are flat, 

 and form a complete mosaic, only 

 a little rough to the feeling, when 

 rubbed with the finger towards 

 the base, and it is of quite the 

 same nature as that covering the 

 ventral side of the rest of the fin 2); 

 the whole surrounding of the clo- 

 aca as well as the space from 

 there to the foremost lateral corner 

 of the fin is naked (with a few 

 scattered groups of teeth); further- 

 more a naked stripe stretches 

 from the hindmost inner edge of 

 the fin-membrane, where the fin 

 is laid against the appendix, some 

 way on the ventral side of the 

 fin. Both edges as well as the 

 whole dorsal side of the appendix 

 are naked. 



The somewhat triangularly 

 pointed terminal part shows, when 

 seen from the dorsal side, the appendix-slit [a/) situated near the lateral edge; a rather large, foliace- 

 ous fold of the skin, which includes the skeletal piece Tdi^ originates from the dorsal lip of the slit; 

 the proximal end of this fold stretches into the (half-) tube formed by the distal ends of the marginal 

 cartilages. Accordingly there will, on both sides of this plate, be an outlet from the canal of the 

 glandular bag in the broad part of the appendix; the real continuation, however, of this canal is 

 here, as everywhere, situated in the terminal part laterally of the .said fold (at aj). If the fold 

 is thrown back, there will in the lateral margin of the appendix-slit proper be seen a rather large 



1) Muller & Heule I.e. p. 99 state in characterising the genus: <;Die Anhange des Mannchen klein unci weichu, 

 which, as we have seen, does not apply to adult animals, and consequently is of no value as a characteristic of the genus. 



2) This dental mosaic on the ventral side is quite different from that of the dorsal side, where the dermal teeth 

 project as small thorns from the thicker skin. The words of Muller & Henle in characterising the genus: t Schuppen 

 konisch in eine Spitze endigend, zerstreut > are then only to be apphed to the dorsal side. I have not upon the whole 

 found any mention made of the dermal teeth of the ventral side, only expressions to the effect that the abdomen is more 

 or less smooth. 



Fig- 13- 



Fig. 13. Rhina sqtiatina. The left appendage from the dorsal side, reduced. 

 The part from a to b has been cut up in prolongation of the appendix-slit to 

 open this latter so much as to get a view of the gland k. /' is part of the 

 entrance to the pocket between Tv and v. 



Fig. 14. A transverse section through the same appendage after the Une, 

 marked with * * in fig. 13. b the transverse section of the appendix-stem. D 

 Musciihis dilalalor. E Musculus extensor. S Muscnlus compressor. k the 

 gland. V blood-vessels. // horn^- filaments, r the end of the last ray. 



