The Emhryohgy of Chlamydoselachus 623 



because the females must have body and blood to manufacture the huge ovarian eggs, 

 and must have a larger body-space to carry during the long gestation period the 8 to 12 

 eggs and embryos such are as portrayed in Figure 49, plate V. 



A mere glance at Figure 52, plate VI, shows a long and slender shark whose head 

 and body from snout to pelvic fin are of approximately the same diameter throughout. 

 This uniform size of body surely enables Chlamydoselachus to creep through the inter- 

 stices of debris at the bottom of the sea that would stop any other shark and almost any 

 large teleost other than an eel. Possibly this very slender body is connected with the 

 feeding habits of the shark. However, this slender appearance must be considerably 

 changed when the fish is gravid or when the ovaries contain nearly ripe eggs (Text-figure 

 7). This slenderness of the body will be emphasized by giving some ratios of total length 

 to depth. Thus a male 1473 mm. long was in length 16.4 times the depth of the body. 

 A non-gravid female 1910 mm. long gave a ratio of 11.5 to 1. A 920-mm. female gave 

 a ratio of 12.3 to 1 — a fair average between the other two. A female measuring 1860 mm. 

 was judged from the figure to be gravid. Her ratio was 7-7 to 1. Lastly a figure of a full- 

 bellied female, also presumably gravid, from measurements of the figure gave a ratio of 

 6.67 to 1. 



Let us now go more into the details of the external form of our fish as seen in Figure 

 52, plate VL The eye is round but the socket is somewhat distorted by the mouth being 

 drawn gaping. The mouth is nearly terminal and the gape is very large in both vertical 

 and horizontal measurements. The briar-like teeth are faintly indicated, but even plainer 

 are the denticles on the lips and the plications in the skin at the angles of the jaws. The 

 gill-covers are frilled, the frills being due to the points of the branchial rays which aid the 

 covers in respiration. The gill-covers of the first pair are continuous across the isthmus. 

 Where the covers are attached to the body are the curious curved surfaces noted in the 

 embryos. Visible are the ends of the gill-filaments. Surely Chlamydoselachus is 

 the ''fringe-gilled'" shark. 



The back of this fish is nearly straight from the top of the head to the insertion of 

 the dorsal fin. On head and cheek are some of the sensory canals and on the side of the 

 body runs the lateral line, normal throughout — including the customary irregularity 

 under the dorsal. The abdomen looks full and leads to the suspicion that this female is 

 possibly gravid. Along the ventral surface of the abdomen are the curious tropeic folds 

 probably functioning as bilge keels. These keels end between the pelvic fins and immedi- 

 ately in front of the cloacal aperture. 



At the junction of trunk and tail and just in front of the caudal fin are the dorsal 

 and anal fins set in a vertical line. Concerning this interesting concentration of the fins of 

 Chlamydoselachus, Gudger and Smith (1933, p. 296) have this to say: ''The close as- 

 sociation of dorsal, anal and pelvic fins with the caudal gives the creature a fulcrum on 

 which to straighten its body in striking forward to seize its prey. This was first suggested 

 by Garman. In ordinary swimming, right and left strokes of the caudal will send the body 

 forward with the sinuous motion common to all slender fishes." 



