The T^atural History of the Frilled Shar\ 277 



Taking then our largest number of teeth, 274 for fish No. I, each tooth with its 3 

 cusps (in theory), we have a total for the mouth of 822 spinc'like fangs— all functional at 

 once. While this count does not equal Carman's estimate of 51 rows of teeth with 6 

 teeth in a row, or 306 teeth (918 cusps), it does present an impressive number of teeth and 

 fangs. In fact it is (so far as we know) exceeded only by the much smaller but vastly more 

 numerous comb'like teeth of the whale shark, Rhineodon typus, which in the jaws of a 40- 

 ft. specimen may number 6000 to 7000; and possibly by those of Cetorhinus maximus, 

 the basking shark. 



The many small teeth of Chlamydoselachus, each with its three slender recurved 

 cusps, evidently function (like the simpler but vastly more numerous and smaller teeth of 

 Rhineodon) for retention only, in contrast with the chopping service rendered by the one or 

 two rows of broad teeth of Charcharodon and Galeocerdo. In conclusion we note that 

 the wide gape, the many hooked teeth, the large shagreen-Lined mouth and gullet, all 

 indicate that Chlamydoselachus may seize and swallow living prey of a diameter nearly 

 equal to its own. 



There are no differences correlated with sex either in the form of the teeth or in their 

 number and arrangement in rows. 



The function of these teeth being clear, the matter of the apposition of the teeth in 

 the jaws must be noted. A priori it was thought that when the mouth is closed a row of 

 teeth in one jaw would fit between two rows in the other. How this may be in the live 

 fish we cannot say, but in our preserved specimens it is not so. It is true that these jaws 

 are somewhat distorted in the hardening process, but in them the tooth rows tend to fit 

 against each other. 



EYES OF CHLAMTDOSELACHUS 



The eyes are large and elongate, and are situated on the side of the head approximately 

 over the space between the fifth and seventh rows of teeth. In Carman's figures (our 

 Text'figure 1 and Figure 16, plate V), the eye is represented about midway between the 

 tip of the snout and the angle of the mouth. This location is true of the eye in our three 

 adult specimens and in the head from Columbia University. A number of the specimens 

 of which figures are reproduced in our paper seem to have the eye in about this position. 

 However, the eye is placed forward of the median point in Lozano Key's drawing (Text' 

 figure 6), and in those of Ciinther and Doflein (Figures 1 and 2 of plate I); also in that of 

 Collett (Figure 6, plate II). Examination of our embryos shows that in them the eye is 

 slightly behind the median point. In this particular matter, either the fish is subject to 

 considerable variation or the artists have been inaccurate in their drawings. 



The eye is elongate in all our adult specimens, but is round in our embryos. Nearly 

 all the illustrations of the fish show it elongate. Notable however are the round eyes in 

 Mertens' (1921) and Ito's (1931) figures (our Text-figures 4 and 5). These we believe 

 to be incorrectly drawn. As may be seen in our Table VI, the aperture is greater in its 

 horizontal than in its vertical diameter. 



