5 8 ON THE APPENDICES GENITALIAS iCLASPERSl IN THE SELACHIANS. 



long, triangular, plate-shaped prolongation, AV, fig. 45, running into the terminal part, and supporting 

 the above-mentioned dermal fold. 



The number of terminal pieces is five , and to these is to be counted a covering piece be- 

 longing to the aponeurosis of the Muse, dilatator. This covering piece 1 ! (fig- 48) is chiefly situated 

 on the dorsal side, has a fairly triangular contour, flatly rounded, with part of the medial edge bent 

 in such a manner that it catches round the medial edge of the end-style (fig. 46, d). This piece quite 

 evidently belongs to the same kind of structures as those, described as covering pieces; in the be- 

 fore mentioned forms [Rhina , Mustelus antarcticits , Torpedo, Narcine, Trygori), only the development 

 Inning here taken place in the dorsal side of the aponeurosis; and so I here (and in other Raja- 

 species) mark it with a d. 



With the distal end of the dorsal marginal cartilage is only connected one piece, proximally 

 also touching the style; I regard it to be corresponding to the Td of the other Plagiostomes, as it is 

 situated in the same manner as that in the dorsal lip of the appendix-slit, and shows the same relations 

 to the marginal cartilage and the stem; it is rather thick, somewhat bent in a crescent-shaped manner 

 with the concavity towards the stem; distally it is firmly connected with the style of the stem by 

 means of an uncalcified (or slightly calcified) cartilaginous prolongation 2 ). With the hinder half of 

 the lateral edge of this piece Td is connected a long, narrow piece, attached by a baud to the terminal 

 end of the style; it is situated in the edge of the dorsal lip, and I think it to be corresponding to 

 the piece, which in several other Plagiostomes I have called Td,. With the ventral marginal carti- 

 lage are terminally and laterally connected two pieces of a peculiar shape. Onlv the medial one of 

 these is also connected with the style of the stem, passing closely along it until the above mentioned 

 calcified bulb x\ this piece then must be corresponding to Tv\ it is rather thin, rounded on the outer 

 side, and prolonged to a slender, bent, obliquely-posteriorly and laterally directed part, ending in a 

 hook (it is this hook, which is seen covered by a loose, mucous membrane in the fig. 24 of the text 

 at Tv). The other piece consists of a crescent-shaped, large part, the concave side of which is for a 

 long way connected with the terminal and lateral edge of the ventral marginal cartilage; most ante- 

 riorly the long horn of the crescent reaches into the appendix-slit; behind and laterally the piece is 

 prolonged to a long, rather slender process, tapering to a somewhat bent, flat part with a slightly 

 notched end (it is this process, which is seen covered by loose, soft membrane in the fig. 24 of the 

 text at Tv 2 ). I take this piece to be homologous with the fully developed piece Tv 2 in Spinax (in 

 Acanthias and Somniosus it is only indicated), and its situation seems to me to settle this homology 

 beyond doubt. Finally is found, belonging to the ventral structures, a verv large piece, rather crescent- 

 shaped when viewed from the ventral side, which must be corresponding to the piece 7 1 , (the v.thorn* 

 or spur in different Sharks); i^'oximally it reaches far into the appendix-slit, is on its medial side 

 broad, flatly rounded, and sends forth laterally a high, sharply winglike ridge with undulating, finely 

 indented edge; somewhat above the middle it sends forth a tap-like process, ventrally overlapping 

 Tv 2 ; distally it ends with a plate resembling the blade of an axe, and ventrallv reaching over the 



M It is mentioned by the way by Moreau I.e. p. 251 under Raja clavata by the name of Cartilage interne^; the 

 presence of Td 2 is also noted here, but this piece gets no special name, as it is not found in R. clavata. 

 2 ) This connection-piece I take to be not independent. 



