260 Bashford Dean Memorial Volume 



DISTINCTIVE MORPHOLOGICAL CHARACTERS 



In this section we endeavor to synthesize the scattered observations of many writers 

 on the morphology of Chlamydoselachus, in order that students may be able to get a clear 

 idea of the general form and make-up of this little-known selachian. The statements of 

 every author have been checked against our three adult female specimens, and for head 

 parts also against the well-preserved specimen from Columbia University. On many 

 points, notably on teeth and caudal fin, because of our abundant material, we have the 

 good fortune to record more extensive data than any preceding students. This part of 

 our article will then form a very definite basis for the future study of the anatomy of the 

 adult and for an exposition of the main features of the outer development of the embryos. 



THE ANIMAL AS A WHOLE 



In studying the natural history of Chlamydoselachus, we must first consider the 

 animal as it would appear to the eye of an observer on first beholding the fish. 



GENERAL FORM AND APPEARANCE 



"Is it a sea serpent?" was the question asked by many who saw Carman's specimen 

 (1884.1) for the first time (Text-figure 1; Figure 16, plate V). The elongate, slender, 

 eel-like body, the flattened sub-triangular head, the sinister eye, the anterior mouth (al- 

 most terminal in position), the enormous gape, and the jaws beset with slender hooked 

 teeth, do give Chlamydoselachus a certain superficial resemblance to the pythons among 

 snakes. But fins and gill-openings at once proclaim that the creature is a fish. Then the 

 shagreen that covers the body and lines the mouth, the multiple gill-straps, and the funda- 

 mental internal structures conclusively show it to be a shark. Yet Chlamydoselachus 

 anguineus ("the snake-like frilled shark") is the most slender and eel-like selachian known to 

 science. Even in our specimens that have been in formalin and alcohol for about thirty 

 years, the body is fairly flexible. 



This extremely slender form may be clearly demonstrated by bringing together the 

 few records of ratios based on length and diameter. Thus Gunther's largest male speci- 

 men (1473 mm. long) was in length about 16.4 times the depth of the body (see Plate I, 

 figure 1); Collett's female fish was 1910 mm. over all and 165 mm. in depth, giving a ratio 

 of 11.5 to 1. Carlos de Braganga's specimen, a male 920 mm. long, was "about" 75 mm. 

 in depth, a ratio of 12.3 to 1, which strikes a fair average between the other two ratios. 



However, there are now to be considered two fish whose dimensions give ratios 

 which depart widely from the above. L. Bertrand's very full-bodied female measured 1860 

 mm. in length and 240 in greatest depth, giving a ratio of 7-7 to 1. This exceptional ratio 

 is to be explained on the ground that the fish is a female and is presumably gravid. We 

 base this conclusion on the full-bellied appearance of the fish as seen in Bertrand's illustra- 

 tion (made from a photograph reproduced as our Figure 5, plate II). For the Japanese fish 

 shown in our Text-figure 5, the proportion of length to depth based on the measurements 

 given is 12.7, but our measurements of the illustration give the figures 267 mm. in length 



