ON THE APPENDICES GENITALES (CLASPERS) IN THE SELACHIANS. 35 



here covered with dermal teeth ; besides the parts mentioned only the surroundings of the anterior 

 aperture of the glandular bag are naked. The points of the dermal teeth are also turned towards the 

 base of the appendix; they are longest and most pointed on the dorsal side of / and /. The appendix- 

 slit is closed (to an extent of abt. 1$™°) in advance of the terminal part, as may be seen by throwing 

 back the dermal lip x — x' in fig. 8; accordingly we have as in Sc.canicula two outlets for the secretion 

 of the glandular bag. 



The skeleton in its main features is as in Sc. canicula, but the appendix-part of it is 

 much more clumsy and peculiarly twisted. One small b Y without rays, and a little t 3 with rounded 

 contour are found '|. 



The appendix-stem, from the articulation with b 1 to the end of the style, is of the same length 

 as the basale; it is somewhat bent with medial concavity; the end-style of about half the length of 

 the calcified stempiece; at the distal end of the former the medial edges of both the adjoining ter- 

 minal pieces form a rather sharp knee. 



The marginal cartilages are principally like those in Sc. canicula; Rd is posteriorly somewhat 

 longer than Rv, and is distally and medially a little hollow. 



The terminal pieces are four, three of them white and hard. Td is formed somewhat like 

 a roof and as broad medially as Tv is ventrally; Td 2 is mainly as in canicula\ Tv is rounded on the 

 outer side, somewhat concave towards the slit, T~ in my specimen is not calcified; but a soft, 

 fibrous cartilage, joining with Tv and placed in the lip /, in my opinion represents this piece 2 ). As 

 in Sc. canicula none of the terminal pieces are seen through the skin. 



The muscular system. From the medial marginal part of the M. adductor have been 

 branched off two separate muscles : fig. 65, fig. 66 a s and a 2 . 



If we look at the ventral side (fig. 65) the fibres of the marginal part are seen as a powerful 

 muscle a It anteriorly originating from the medial aponeurotic stripe, and posteriorly inserted on the 

 proximal part of the appendix-stem close to the ventro-lateral edge of the skeletal orifice for the 

 glandular bag; but part of its fibres attaches to the basale, and another part runs into the M. dilatator. 

 Looking at the dorsal side (fig. 66) we find the edge formed by another muscle a 2 , anteriorly only 

 indistinctly separated from a z , but posteriorly distinctly enough, as here a foremost portion of the 

 J/, dilatator originating from the medial side of the basale, wedges in between both. This muscle a 2 

 distallv joins with the M. extensor (E), and together with this is inserted by a tendon below the 

 knee of the appendix-stem. 



The M. dilatator is enormously thick, and originates with the greater part of its mass from 

 the appendix-stem until the boundary of the marginal cartilages, but, as already mentioned, a portion 

 of it arises from the medial side of the basale; part of this muscle distally joins in the composition 

 of the peculiar process f (it is the same in Sc. canicula, where this process is much less conspicuous), 

 which by no means, as Petri says, is composed exclusively of verfilztem Bindegewebe>. 



') Petri 1. c. fig. 7 C has distally of fl (r in Petri) another little piece (r"), which is not found at all in my specimen, 

 and which upon the whole I do not think to be normal (originating from a rupture?); furthermore a piece [mr) which he 

 (p. 3051 compares to a knee-cap »; this is, however, scarcely to be regarded as a particular piece, but, I suppose, only a strongly 

 calcified eminence on the stem. 



2 ) Petri, fig. 7 C, x. 



