ON THE APPENDICES GENITALES iCLASPERS) IN THE SELACHIANS 



such a wav, that its concave side Hke a roof covers the lateral edge of the piece h^; with its hind- 

 most corner it is b}- means of tight connective tissue attached to the lateral surface of this piece; its 

 medial edge is free, and forms the limit 'of the tight foremost part of the appendix-slit, as it also, 

 together with the process x of the piece b^ , contribiites to the bordering of the aperture, in which the 

 slit opens anteriorly. We find thus between Chimcera and most likely all the Holocephales [Callo- 

 rhynclms shows the same relations) on one side and the Plagiostomes on the other the great difference 

 that the appendix-slit anteriorly stretches over the piece /J, and on the dorsal side separates this piece 

 from the other parts of the stem skeleton. 



The appendix-stem /; is joined to b^ by an onh" slightly movable articulation , and forms the 

 whole terminal skeleton; no secondary cartilages are found, and consequently the terminal part cannot 

 be directly homologized with that in the Plagiostomes. The part of the appendix-stem lying in the 

 shaft, is short, medially flattened; its medial surface is continued directly in the prolongation forming 

 the medial branch of the terminal jjart; in the lateral surface is found a furrow-shaped hollow contin- 

 uing the furrow in /;, ; both edges of this furrow are elevated and bent towards the concavity, what 

 especially applies to the ventral edge, which rises very much, bends quite over on the dorsal side, 

 folding over the edge of this latter, and lying close to the medial continuation, following this latter 

 quite to the end as the skeleton of the dorsal branch of the terminal part; laterally it forms the car- 

 tilaginous prolongation supporting the lateral branch of the terminal part. 



That the cartilage of the medial branch of the terminal part is homologous with tliat part of 

 the appendix-stem, which in the Plagiostomes I have called the end-style, is an obvious conclusion, 

 and admits of no doubt. At a first glance it seems also obvious that the plate-shaped, folded ventral 

 edge with the two other branches must be corresponding to the ventral marginal cartilage in the 

 Plagiostomes, which latter frequently in Sharks recalls it by the plate that is bent in a .similar 

 manner; it might even be temjjting to continue, and take the two branches, the dorsal one and the 

 lateral one, to represent two terminal pieces (resp. Tv and Zl) coalesced with the ventral marginal 

 cartilage; or it might be supposed that this part of the skeleton in C/iiincrra was representing a stage 

 where the terminal pieces had not yet been articulated off as independent parts'). But a closer exa- 

 mination shows that the idea of these homologies must be dismissed; the folded ventral edge with 

 its two prolongations is in ChinKFra absolutely one with the other appendix-stem, consists like this of 

 the same kind of hyaline cartilage, which is corroborated by a transverse section; as a homologon of 

 this structure in Cliinurra the question can only be of the more or less distinct ventral bordering ridge 

 on the appendix-stem in the Plagiostomes, bearing and continuing the ventral marginal cartilage (see 

 for inst. the Greenland Shark). In the firm, liplike edge of connective tissue, which in Chiuucra follows 

 the dorsal cartilaginous edge of the appendix-slit, an indication is found that ma}- possibly be regarded 

 as homologous with the dorsal marginal cartilage in the Plagiostomes. 



The muscular system. I shall only here describe the muscles that are of importance with 



') This ha.s also been intimated by Gegenbaiir 1. c. p. 455; at the same place he intimates that his supposition that 

 the terminal pieces in tlie Sharks are transformed ra\-s may possibly be wrong, since in C/tiiiicrra the branches are in contin- 

 uous connection with part of the stei:i-skeleton. 



