ON THE APPENDICES GENITALES (CLASPERSI IN THE SELACHIANS. 



2. Special Part. 



SelachoideL 



Spinacidce. 



Acanthias vulgaris Risso. 



I PI. I. Kg. i", 1 1.) 



The common picked Dog-fish has been so often examined that I think a more particular de- 

 scription of the external features of the copulatory appendages to be superfluous; I may refer to 

 Petri 1 ) (with regard to whose description, however, I must remark that the investment with dermal 

 teeth at the places of transition to naked parts does not cease gradually, but is quite sharply bounded; 

 the dorsal side is wholly naked, as is also on the ventral side the hindmost point of the terminal part), 

 as also to the earlier description by Bloch-) and Home'). In a specimen of the length of (>j :,: the 

 following measures were found: 



Length of the appendix (from the fore-edge of the cloaca i . . 



part free of the fin 5> r ' 



terminal part 2, 2C: " 



appendix-slit 4,-'" 



Breadth of the appendix ab. r c,n 



The skeleton has not been quite correctly described by any of the earlier authors.!. 



Between the basale and the appendix is found only one short joint (/',), and besides the dorsal 

 piece /?5); this latter articulates anteriorly witli the basale, posteriorly with the appendix-stem /<. and 

 medially with /•>, ; its lateral edge is convex, projecting somehwat in the shape of a roof over the two 

 hindmost rays; these ravs are borne by the piece /', , and are often coalesced; they are stronger and 

 longer than the last ray but two, which latter comes from the basale. 



The stem of the chief piece of the appendix has a length like />'—/>,, and proximally towards 

 its articulation with />, is found a ridye (at b in fig. 10) projecting in a somewhat keel-like mam 

 in the hindmost half it has laterally a little trough-like hollow. The soft end-style is short"), flatly 

 rounded, and reaches not nearly to the end of the terminal part. The dorsal marginal carl 

 (Rd) can forward be indistinctly traced as a rounded ridge to about the letter v in fig. 11 lit is 1: 



'I I.e. p. 300, pi. XVII, fig. 5, A. 



-\ 1. c. 17SS, p. 9, pi. 2, fig. 1. 



3) On the Mode of breeding of the Ovoviviparous Shark etc. Phil. Trans. 1S10, Pt. II, p. 205, pi. I\ 

 lastmentioned place the ventrals and the appendages have been drawn in a position, which they scarcely naturally would 

 he able to have. 



ii Drawings are found not only in Bloch, Gegenbaur and Petri, out also in Molin: Sullo scheli 

 Squali, pi. Ill, fij;. 7; Memorie dell' 1st. Veneto, vol. S, 1859, but without any explanation or description in the text 



; i Gegenbaur, fig. 16. Ii\ Petri, fig. 5 D, >■' . 



'1 Gegenbaur, fig. 17, i\ it has been quite overlooked by Bloch and Petri 



71 Mentioned neither h\ Gegenbaur nor Petri. The hindmost end oi it is the 

 (1. C fig. 3) of Bloch. Neither of these authors have seen independent marginal cartilagi 



