NO. 3537 SHARK GENUS ISURUS — GARRICK 673 



the number of teeth has been discussed on page 666 ; I do not find any 



of the other so-called differences to be valid. Philippi (1887, p. 548) 



distinguished his eastern Pacific /. huidohrii from Lamna cornubica by 



its teeth. He implied the need for comparison vnih I. spallanzani, 



but otherwise there is no discussion of diagnostic features. Whitley 



(1929, p. 101) named the New Zealand /. mako on the characters 



given in PhiUipps' (1926, p. 530) account of /. glaucus. Phillipps 



compared his material with /. glaucus of Mtiller and Henle and with 



that of Waite (1921, p. 21) which was, in fact, a specimen of Lamna 



nasus. The only character which Phillipps thought distinctive was 



the relative lengths of the dorsal and ventral lobes of the caudal fin. 



His figure for these, 1.27, comes well within the values given here 



(table 1, J) for other short-finned makos. Phillipps (1932, p. 227) 



named the South African /. bideni using the description in Whitley 



(1931, p. 140). He distinguished /. bideni from /. mako and /. 



glaucus on the height of the first dorsal fin, the shape and dimensions 



of the caudal fin, and the position of the anal fin, viz, "Anal base 



wholly behind second dorsal." Of these three, only the last-mentioned 



character is unusual. I have found no mako with the anal fin as far 



back, relative to the second dorsal fin, as Phillipps shows in his figure 



of I. bideni, and presume that the figure is inaccurate in this feature. 



Smith (1957, p. 96) provisionally proposed the subspecies /. tigris 



ajricanus for a 2,540 mm. specimen from South Africa on the grounds 



that its first dorsal fin was less acute apically and slightly lower than 



Atlantic and Australasian specimens of /. tigris. In a later account 



Smith (1958, p. 134) recognized his subspecies as 1. ajricanus but 



without further clarification of its distinctive features. As can be 



seen from figiure 3 in the present account, /. ajricanus does not merit 



specific status in regard to its first dorsal fin height. 



Cadenat (1962, p. 305) has suggested the probability that a further 



and as yet unnamed species of Isurus is present in the tropical Atlantic. 



This Isurus, which Cadenat knew only from the head of a specimen 



taken by a Japanese long-liner south of Cape Verdes Islands, differs 



from other makos in the number and arrangement of the upper teeth. 



8—2—2—8 

 Its dental formula is . In the upper jaw there are two large 



teeth close together on each side of the symphysis, followed by a dis- 

 tinct space separating them from the smaller lateral teeth. In aU 

 other makos, including the new species described on p. 677, there are 

 similarly two large teeth on each side of the symphysis, but these are 

 closely followed by a noticeably smaller tooth which in tiu-n is sep- 

 arated by a space from the larger lateral teeth. Also most makos have 

 more lateral teeth than Cadenat's specimen. The first upper tooth of 

 Cadenat's specimen has an incomplete cutting edge along the lateral 



