ON THE APPENDICES GENITALES (CLASPERS) IN THE SELACHIANS. 65 



The skeleton. Between the basale 1 ) and the appendix-stem, as in all AV/y-species, are found 

 a /', , a A, and a j8 2 ); A also here bears the last six rays. The appendix-stem is about twice as long 

 as B + /', -f 6 2 , flattened especially distally; its terminal part, being as usual uuealcified, here forms 

 an s-shaped , quite thin , flat style broadening towards the end. As in the other Ra/a-species the 

 dorsal marginal cartilage stretches forward almost to the beginning of the stem, but backward not so 

 far as the ventral one; this latter, especially distally, is a good deal broader. To the inner side. of 

 the dorsal marginal cartilage, at its distal edge, is articulajted a triangular cartilage Rd' (fig. 56); it 

 is quite corresponding to the one marked Rd' in the two other Aff/tf-species , in which, however, it is 

 only a direct prolongation, a process, from the marginal cartilage itself. 



The number of terminal pieces is five, exclusive of the covering pieces. Three covering pieces 

 </,, d 2 , d 3 are found on the dorsal side. The lateral one, d t , is a good-sized, externally rounded 

 plate, with a bow-shaped, convex lateral edge folding round to the ventral side. Its medial edge is 

 rather straight and firmly connected with d 2 , which latter as a narrow band runs obliquely across the 

 terminal part, and tapers towards the medial end that is bent round to the ventral side, and by a liga- 

 ment attached to the point of the piece T 3 (see fig. 55). The third covering piece , d 3 , is connected 

 with the lateral end of the preceding one; it is of a triangular, externally somewhat rounded shape, 

 and by a ligament attached to the hindmost end of the appendix-style; with its inner surface is is 

 connected with the dorsal side of the piece Td 2 . The three mentioned covering pieces have all arisen 

 from the same aponeurosis of the M. dilatator, and accordingly they together represent the single 

 covering piece d in the Skate and the Thorn-back. 



Of real terminal pieces two are found in the dorsal lip: Td and Td, (see fig. 54, 55). Td is 

 short; it is with its whole fore edge attached to the dorsal marginal cartilage, with its foremost 

 medial corner also to the appendix-stem; from its medial-distal corner it sends forth a soft, cartilagi- 

 nous part which farther backward is coalesced with the style (comp. the Skate); else its distal edge 

 is connected with 7V 2 , a proximally broad, distally narrow and tapering, very hard, somewhat s-shaped 

 cartilage; it is outwardly rounded, inwardly concave, and ends in the above mentioned thorn projecting 

 naked from under the edge of the dorsal lip. 



To the ventral side belong three terminal pieces: Tv, Tv 2 , and T. The two first of these 

 are very peculiar, and can only be rightly seen when the skeletal parts are disunited (see fig. 57). 



Tv consists of two parts, a body and a long process; the body is proximally attached to 

 the edge of the ventral marginal cartilage, with one edge to the medial edge of the style (see fig. 54), 

 and with the opposite one to the piece Tv 2 ; from the ventral surface of the body the process arises, 

 and forms together with the «body a kind of T; this process is bent in an irregularly s-shaped manner, 

 ends in a fine, hook-shaped thorn, and is situated in the deep, spoonlike hollow formed by the piece Tv 2 . 



Tv 2 is still more peculiar; its chief part forms an oval spoon, outwardly strongly rounded, in- 

 wardly very deeply hollowed , from the foremost part of which a large, half-moon-shaped part arises join- 

 ing the inside of the ventral marginal cartilage of the appendix-stem; the lateral edge of the spoon» 

 is prolonged into a not quite calcified, winglike process; between this process, the half-moon-shaped 



■) Bloch 1. c: < der erste Knochen des Sehenkels , fig. 1, /. 



2) i, =^ der zweite . 6 2 = der dritte , ,3 = der vierte Knochen des Sehenkels , fig. 1, m, 11, o in Bloch . 



The Ingolf-Expedition. II, _■. 9 



