The Anatomy of Chlamydoselachus 



The skeleton consists of a main stout bar of supporting cartilages, the myxapterygium 

 [sic], with three additional minor cartilages, of which a pair on either side stiffens the apical 

 expansile valves, the remaining one acting as a foundation for the supposed rhipidion. Two 

 of the radial cartilages attached to the basipterygium, part of which is seen in the upper portion 

 of the figure, come down to support the walls of the clasper cavity. 



377 



Text-figure 47- 



Skeleton of a clasper (myxopterygium) of Chlamydoselachus anguineus. 



a, principal cartilage; al, intermediate cartilage; b, basals of pelvic fin; !, lobe-like expansion of cartilage a; r, rl 



and r2, rays of pelvic fin; t, tl, movable calcified terminal pieces by which the canal can be opened or closed. 



After Giinther, 1887, Figs. D and Dl, pi. LXIV. 



Giinther (1887) states that, as compared with other elasmobranchs, the skeleton 

 of the clasper of Chlamydoselachus (Text'figure 47) is extremely simple and is very similar 

 to that of Acanthias as figured by Gegenbaur (1870, Fig. 15, Taf. XVI). Goodey (1910.1, 

 p. 567) writes: 



When the mixipterygium [sic] of Chlamydoselachus is compared with that of Hexanchus 

 griseus, described and figured by Huber, one is at once struck by the high degree of develop- 

 ment presented by the organ in Chlamydoselachus. Whereas in Hexanchus the axial cartilage 

 is represented by a comparatively short cartilage, scarcely distinguishable from a lateral 

 radial, and bearing no accessory cartilages; the homologous part in Chlamydoselachus is 

 a long, stout cartilage, furnished distally with three movable accessory cartilages. 



As described by Daniel (1934) and as shown in my Text-figure 45b, the skeleton of 

 the myxopterygium of Heptanchus is somewhat simpler than that of Chlamydoselachus. 

 The skeleton of the pelvic fin of a male Raja (sp.?) figured by Gegenbaur (1870, Fig. 21, 

 Taf. XVI) is simpler than any that I have mentioned. Evidently, differences in the form 

 of the skeleton of the claspers are of little phylogenetic significance. 



THE DORSAL FIN 



In the single dorsal fin of Chlamydoselachus, the cartilaginous elements (radials) 

 forming the endoskeleton are very irregular, as shown in my Text-figure 48. The tapering 

 anterior portion extends a considerable distance in front of the small membranous portion 

 of the fin. Garman (1885.2, p. 15) interprets this condition as follows: 



