48 



ON THE APPENDICES GENITALES (CLASPERS) IN THE SELACHIANS. 



Length from the foremost end of the slit to the extremity . . 4o mm 



— of the free part ij mm 



The greatest breadth ca. io mm 



The length of the terminal part 15™" 



In another specimen of the same length and a breadth of 19™ the appendages were a little 

 shorter and broader, bnt otherwise as fully developed. 



The skeleton. Between the basale and the appendix- 

 stem are found two pieces b z , 6 2 , of which the former is the 

 shorter one (seen dorsally it is much shorter), and bears the two 

 hindmost rays (the last but one is partly borne by the basale 

 also). The piece jit is long, longer than b 2 , flat; proximally it 

 articulates with b z , runs along b, without touching it, and arti- 

 culates distally by an oblique articulation with the appendix-stem 1 )- 

 The appendix-stem is rather straight, calcified in the sur- 

 face until the terminal part, where the mosaic of the surface sud- 

 denly ceases, and the outermost part of the stem is soft, which 

 soft part, chiefly of the same breadth as the harder one, thus 

 corresponds to the style, and reaches to the end of the terminal 

 part, ending with a broadly rounded, convex edge. 



The marginal cartilages are both calcified, but very un- 

 equally developed, by which the whole appendix gets a peculiar asymmetric appearance; the ventral 

 one 2 ) reaches a trifle longer forward than the dorsal one, but backward it ceases far before this latter; 

 the dorsal cartilage is by a longitudinal furrow apparently divided into two pieces of which the lateral 

 one begins forward about the middle of the ventral cartilage, and stretches backward about as far 

 past the hinder end of this latter (see fig. 30, 31); this part of the dorsal marginal cartilage is on the 

 ventral side hollowed in a trough- or groove-like manner; the medial part of this cartilage, especially 

 the foremost part of it, is slightly calcified, membranous, and is placed like a cover over the appen- 

 dix-slit, so that a narrow slit is left between its outer edge and the ventral marginal cartilage. 



Fig. 19. 



Fig. 20. 



P*ig. 19. Torpedo marmorata. Part of 

 the skeleton of the right ventral, from 

 the ventral side, r the hindmost rays 

 partly cut off. Natural size. 



Fig. 20. The same preparation from 

 the dorsal side. 



*) Petri has quite misunderstood the relations of these skeletal pieces, and has upon the whole been very unlueky 

 in his explanation of the skeletal pieces in Torpedo. Already his beginning: « Das Skelet von Torpedo besitzt nur sehr ge- 

 ringe Ahnlichkeit mit dem der vorher beschriebenen Arten , promises nothing good; and his description of the terminal 

 parts shows that he has not understood them at all. He has correctly seen that between the basale and the appendix are 

 situated two pieces: fig. 4D, b\ 6", but their length and position is given less correctly in the figure, which is, like all his 

 figures, rather bad; but then he has completely overlooked the piece ji as a separate skeletal part taking it to be a process 

 on the appendix-stem: Nach vorne entsendet dasselbe (i.e. the appendix-stem) an der medialen (i. e. the dorsal) Seite neben 

 dem zweiten uud dritten Glied des Basale entlang einen Processus, welcher mit dem ersten Basale am hintereu Elide uoch 

 in Verbindung steht . As a honiologou to the piece /J in Acanthias (Petri's fig. 5 r) he takes a little piece (fig. 4 D, r), which 

 is said to bear the two last rays and to have originated from a coalescing of the proximal joints of those: <es ist dieselbe 

 Concrescenz, wie ich sie bei Acanthias beschrieben habe . In Acanthias, however, the piece /9 [r in Petri) bears no rays, 

 as, after all, it never does. The little piece which Petri has seen in Torpedo (and in the figure marked r), is only an 

 1111 calcified corner of the basale itself, projecting over the two last rays, but it does not bear the rays. 



2 ) The marginal cartilages are partly correctly seen and determined by Petri as < Riniienknorpel : Fig. 4 D and E, 

 c and /; F, /; (and pi. XVII, fig. 4 B, /); the skeletal piece, however, interpreted by Petri as a dorsal marginal cartilage and 

 marked /, is only the firm lateral part of the dorsal marginal cartilage; the thin, cover-shaped part seems to be removed, 

 except .hi fig.4 B, representing the muscles. 



