4 6 



ON THE APPENDICES GENITALES (CLASPERS) IN THE SELACHIANS. 



as, however, no figure is given of the part in question, seen from other sides, I cannot regard this absence as quite 

 certain. The long appendix-stem is prolonged to a style reaching to the end of the terminal part. The marginal 

 cartilages (not understood by Giinther to be particular pieces) appear to have mainly the same structure as in the 

 Spinacidae ; the ventral one has the usual overlapping plate ( I. c. T. LXIV, fig. D, D' , I). The number of the terminal 

 pieces is only two (if not a piece T h has been overlooked or removed by the preparation?) viz. Td and Tv , both 

 hard and calcified , Tv being as usual largest and broadest. 



Rv- 



Carchariidce. 



Mustelus antarcticus Gthr. 



A pair of dried skeletons of ventral fins with appendages in the Zoological Museum at 



Copenhagen. 



Between the basale and the appendix-stem one rather small piece 6 t bearing the last ray, 



which is partly coalesced with the last but one; a distinct, well developed ft that seems to have been 



triangular. The appendix-stem is prolonged to a long, 

 soft style reaching almost to the hindmost end of the 

 terminal part. The marginal cartilages stretch over the 

 hindmost two third parts of the chief piece, the dorsal 

 one reaching farther forward than the ventral one; the 

 edges of their folded parts join dorsally, leaving between 

 them only a narrow slit. To the distal end of the dorsal 

 marginal cartilage is added a foliaceous, slightly calcified 

 piece, homologous with the piece Rd 2 mentioned in Pri- 

 stiurus. 



The number of terminal pieces is 4 (-f- 1). 

 The two of these pieces that as usual follow the 

 style, and together with it form the walls of the hind- 

 most part of the appendix-slit, Td and Tzi, are well cal- 

 cified, lengthened, pointed, and Td a little longer than Tv. 

 To the lateral edge of Td is proximally added a foliaceous, 

 slightly calcified piece Td 2 , forward stretching under the 

 piece Rd 2 into the appendix-slit as in several other Sharks. 

 Finally there is a rather large, flat, triangular, posteriorly 

 taplike piece 7\ that, however, does not not appear to 

 have projected through the skin as a spur . 



Besides these real, typical, terminal pieces still a 

 special piece, 7', is found, which I take to be corresponding 

 to the one marked with the same letter in R/iii/a, and 

 accordingly to have arisen from the aponeurosis of the 



Muse, dilatator; here in Mustelus antarcticus it covers a peculiar, rather deep, spoonlike hollow on 



Tv -- 



Eig. 17. 



Fig. is. 



Fig. 17. Mustelus antarcticus. Skeleton of the 

 right appendage, seen from the ventral side; about 

 tin.- natural size, v the ventral covering piece; * 

 a spoon-like hollow in the ventral marginal car- 

 tilage. 



Fig. iS. The same preparation from the dorsal 

 side; * the bottom of the hollow in the ventral 

 marginal cartilage, protruding into the appendix- 

 slit. Both figures have been drawn after the dried 

 .skeleton. 



