?iatural History of the Frilled Shar\ 291 



cent of the total length. The tail of No. II is 555 mm. long, the total length 1485 mm. 

 The tail then equals 0.37 of the whole length. In No. Ill, the "over all" length is 1550 

 mm., and the tail measures 650 mm. or 0.42 of the whole length. These proportions are 

 startling, but they have been taken over and over again until we are sure that they are 

 correct. One has to see the fish to realize just how much of it is tail (not merely caudal fin). 



THE FINS OF CHLAMTDOSELACHUS 

 The fins are very soft and flexible, and while primitive in structure they are typically 

 elasmobranch in character. From the natural history point of view, the most interesting 

 facts about them are the absence of the first dorsal; the bunching of the pe Ivies, the anal 

 and the single dorsal well behind the middle point of the body; and lastly the peculiar 

 shape and structure of the tail and the taihfin. 



PAIRED APPENDAGES 



Like most fishes our shark has both pectoral and pelvic fins. As in Elasmobranchs 

 generally, the pelvic fins are modified in the male to form the claspers or copulatory organs. 



Pectoral Fins. — The low-placed pectoral fins are of moderate size and are broad and 

 rounded. Both front and hinder margins are convex — the hinder one the more so — and 

 these curves meet at the extremity of the fin in an obtuse angle. This is true of the three 

 adults and the six embryos in the American Museum, and it is the form portrayed in all 

 the figures reproduced herein, save Gunther's (Plate I, figure 1) where the fin is shown in 

 oblique view. These fins are remarkably flexible in comparison with the pectorals of 

 other sharks. 



Pelvic Fins. — These fins are placed somewhat behind the middle point of the body, 

 measured from tip to tip. They are larger than the pectorals and are even more broadly 

 rounded. The base of each fin is unusually broad, in the female equalling about twice the 

 depth. These proportions are found in our embryos and are portrayed (sometimes im- 

 perfectly) in the figures already given. The elongate base is especially well shown in 

 Collett's figure of his female specimen reproduced in our Plate I, figure 3. Garman (1885.1, 

 p. 4) says that in his female specimen each pelvic fin "ends in an acute point behind the 

 vent," as may be seen in our Text-figure 1 and Figure 16, plate V. We find this true in our 

 specimens, although the point is hardly so acute as is shown in Garman's figure. 



Myxofterygia. — In the male, the bases of the pelvics are even longer than they are in 

 the female, since in the male these fins are modified to form the claspers, copulatory organs, 

 or myxopterygia. In fact, the edges of the fins reach nearly to the ends of the appendages. 

 In Chlamydoselachus these organs were first studied and figured by Gvinther (1887), but 

 since they do not show in his drawing of the entire fish (our Plate I, figure 1), because the 

 body is drawn with the tail bent to the left, Giinther had them figured in ventral view 

 (Figure 17, plate V). So far as we know, there are but three other figures of male 

 specimens: Doflein's (1906) from Japan, Bolivar's (1907) from Spain, and Goodrich's 

 without designation of source. Both Doflein's and Bolivar's figures (Plate I, figures 2 

 and 4) portray the claspers as being much larger than they appear in Giinther's drawing. 



