68 ON THE APPEXDICEvS GENITALES (CLASPERS) IN THE SELACHIANS. 



On the dorsal side are foiuid two real terminal pieces (see fig. 41, 42), Td and Td,. The former 

 is for a long way connected with the dorsal marginal cartilage and with the appendix-stem; from the 

 hinder end it sends forth a long, ronnd, somewhat finger-shaped, bent process with ronnded end, and 

 rnnning obliqnely towards the ventral side; on the dorsal side only a little of the basal part of this 

 process is seen, while a larger part may be seen from the ventral side (comp. fig. 44 Td). With the 

 onter hindmost corner of Td a piece Td^. articulates, dividing behind into two branches, an inner one, 

 short and soft, attaching to the appendix-style, and an outer one, hard, compressed, produced to a 

 fine point (corresponding to the free thorn on the corresponding piece in R. radiafa)\ this latter 

 branch is best seen from the ventral side (fig. 44, 71A), as it is dorsally hidden by the covering 

 piece a'j. 



The ventral lip shows three jiieces: Tv ^ 7r',, and Tl. 



Tv (fig. 42) is slender , anteriorly connected with the terminal end of the ventral marginal carti- 

 lage, which is folded round to the dorsal side; next it follows for a long way the appendix-style, then 

 folds ventrally round this as a rather thin prolongation (fig. 44), and ends finally with two small, diver- 

 ging points at the opposite edge of the style (comp. R. batis). This piece Tv is in its foremost part 

 laterally connected with the very large Tv^. This latter is somewhat half-moon-shaped, and is attached 

 with its foremost concave edge to the ventral marginal cartilage; it sends forth two processes; a short, 

 truncate one close to the medial edge, and laterally of this a long one, bent in the free end like a hook 

 (comp. R. hatis\ the point of which is turned into the appendix-slit (dorsally); the piece Ti',, on its 

 inner side, towards the slit, is of a flat, spoonlike shape. 



T, (fig. 43) is narrow, falcate, and its foremost end is situated under the lateral edge of Tv, in 

 the appendix-slit, between Tv^ and Td\ in its hindmost third part it bears on its medial, concave edge 

 a process corresponding to the -articular head; on 7", in R. radiafa^ but in the present species it 

 passes into a .sharp, winglike edge stretching to the distal end of the piece; the lateral, convex edge of 

 7^3 is sharp and cutting. 



Holocephala. 



In the males of the Holocephales, as is well known, three particular organs are found that 

 are supposed to subserve the copulation, viz.: i) the peculiar cephalic organ') provided with der- 

 mal teeth, 2) the pelvic appendages, i.e. the two organs placed in a ventrally open pouch on 

 each .side before the ventrals, and whose skeleton is connected with the pelvis by an articulation; and 

 3) the ventral appendages. Onl)- the two last-mentioned sets of organs, and especiall)- the ventral 

 appendages, which correspond to those of the Plagiostomes, will be mentioned more thoroughly. 



') This, however, is wanting in the genus Harrioila Goode & Bean, the appendices of which are also said to be 

 csniall and simple* ; of its pelvic appendages nothing is said (Oceanic Ichthyology : Mem. JIus. Comp. Zool. Harvard Coll. 

 vol. XXII, 1S96, p. 32). 



