ON THE APPENDICES GENITALES (CLASPERS) IN THE SELACHIANS. 



distinct, when the piece is dried); posteriori}- it is distinctly elevated as an edge of the appendix-slit. 

 The ventral marginal cartilage {Rt>) is shorter, resembles the corresponding one in the Greenland 

 Shark, and has, as in the latter, a plate-like part 1 ) folded to the dorsal side; on the concave inner 

 side it has furthermore a strong, elevated process; in the furrow between this process and the folded 

 part the proximal end of the thorn is placed. 



There are four terminal pieces. 



Td 2 ) is narrow, with the foremost part of its medial edge closely connected with the end-style, 

 and behind this with the edge of the ventral piece Tv; distally it takes the form of a flattened, sharp- 

 edged hook; this hook-shaped part rises uncovered through the skin, is smooth, shining, and dentine- 

 like. Td is with part of its lateral edge connected with a quite thin, plate-formed piece 3), Td 2 , also 

 anteriorly connected with the marginal cartilage Rd; it is placed in the skin forming the dorsal lip 

 of the appendix-slit of the terminal part, and corresponds to the piece Td,, indicated in the Green- 

 land Shark. 



The ventral terminal piece, Tv4), is considerably broader and longer than the dorsal one, 

 rounded on the ventral (outer) surface, hollowed like a spoon towards the appendix-slit; except the 

 hindmost ]3art it is firmly calcified; the foremost part of the medial edge is connected with the end- 

 style, and behind this with Td, the hook of the latter lying freely in the outermost spoon-like end of 

 the former piece; in the proximal end it has medially an articular process for articulation with the 

 above mentioned process of the concave side of the marginal cartilage Rr, and its lateral edge is 

 firmly connected with a strong, thin membrane (fig. n, Tv 2 ), serving in the foremost part for attaching 

 the outer lip-muscle of the glandular bag; this membrane then corresponds to the similar, but thicker 

 one in the Greenland Shark, and to the piece Tv 2 in Sjhinax. 



The fourth terminal piece, T 3 , is the one called the < spur» 5) by the different authors; with the 

 proximal, somewhat head-shaped end it is attached inside of the folded plate of the marginal cartilage 

 Rv to the above mentioned process, and to the proximal and lateral end of the piece Tv; it is formed 

 as a triangular thorn or spine, longitudinally somewhat twisted, with two concave surfaces; it is firm, 

 shining, dentine-like, and the greater part of it is uncovered by the skin. It can be moved quite in 

 the same manner as the corresponding spine in the Greenland Shark. 



The muscular system. The M. adductor shows the general typical relations. The M. extensor 

 reminds very much of the same one in the Greenland Shark; as in the latter it has here its origin 

 on the medial side of the basale and b u stretches over the «knee of the appendix-stem as a thin, 

 flat covering over the M. dilatator, and inserts itself along the boundary line of the dorsal marginal 

 cartilage. 



The M. dilatator originates proximally with a dorsal portion at the same place as the M. extensor 

 and quite covered by it, that is to say some way up on the basale; on the ventral side its proxi- 



n Bloch, Processus d\ Gegenbaur, fig. 15. 16, a; Petri, fig. 5, D, E, pr\ regarded by all only as a process 011 

 the chief piece. 



1 Bloch, der Haken, fig. 2, c, fig. 6; Gegenbaur fig. 16, 17. a; Petri, fig. 5. hk. 

 )) Petri, fig. 5, la; it is neither mentioned nor drawn by Bloch or Gegenbaur. 



4) Bloch: der breite Knochen, fig. 2, d, fig. 5; Gegenbaur, fig. 15 — 17, c; Petri, fig. 5. &"', he interpreting it as 

 tlu- terminal joint of the stem. 



Bloch, der Sporn, fig. 2, c, fig.4; Gegenbaur, fig. 15, 16, a'; Petri, fig. 5, sp and ca. 



