SHARK GENUS ISURUS — GARRICK 



669 



makos which I have seen, the underside of the snout and around the 

 Hps is at least partly dusky. Lesson states that the caudal fin is 

 deeply forked, the dorsal lobe with a "haut de 15 pouces," the 

 ventral lobe with a "haut a peine de 8 Pouces." I assume that by 

 "haut" Lesson meant the length of each lobe from its origin to tip. 

 If this is so, Lesson's stated length of 15 inches for the dorsal lobe on 

 a 6-foot long specimen is in agreement ^\dth other makos. But his 

 stated length of 8 inches for the ventral lobe would be far too short. 

 In all my material the length of dorsal lobe divided by the length of 

 the ventral lobe ranges from 1.19 to 1.54, whereas in /. cepedii it is 

 1.88. The difference is sufficient to throw considerable doubt on the 

 validity of Lesson's measurements, and in consequence of this, plus 

 the discrepancy in snout color and the lack of type material to pro- 

 vide confirmation, I cannot regard the evidence as warranting the 

 recognition of /. cepedii as a long-finned mako. 



Figures 3, 4, 5, and table 1 were constructed from data on short- 

 finned makos only. In figiu-es 3-5 individual specimens are plotted, 

 while in table 1 the data is summarized for three size gi'oups, plus 

 the types wherever possible. The various proportions represented 

 in the figures and table are those which have been used by recent 

 authors, particularly Bigelow and Schroeder (1948), and Smith 

 (1957, 1958), as diagnostic criteria for the several species of Isurus 

 they recognize. In summary, these diagnostic criteria are based on: 

 the proportions of the first dorsal fin (height relative to base), its 

 position and its shape; the height of the first dorsal fin relative to the 



o 



^ 



gomphodon 



tigr,s-0 



• 



W ©— africanuS 



o 



*°***^ 



o 



bidenl 



• 



glaucus 



**. 



o 



cepedii 



A 



huldobrii 



guenlheri 



1000 



1500 2000 



TOTAL LENGTH IN MM 



2500 



3000 



Figure 3. — hums, short-finned only, showing growth change in height of first dorsal fin 

 relative to total length (identified specimens are types of nominal species). 



