Fishes of the Wester ti North Atlantic 309 



Red Sea and Gulf of Arabia; India; Indo-China; North Australia and Queensland; 

 Micronesia. 



Species. Medium-sized tropical sharks of littoral waters; one species so far known 

 from the Atlantic; four from the Indo-Pacific. 



Key to Species 



I a. Snout obtusely wedge-shaped. 



2a. Posterior margins of pectorals and pelvics deeply concave. 



queenslandicits Whhlty, 1939. 

 Queensland, Australia. 



2b. Posterior margins of pectorals and pelvics only very weakly concave. 



fronto Jordan and Gilbert, 1882. 

 Pacific coasts of Mexico and Costa Rica.^ 



lb. Snout broadly and evenly rounded. 



3a. Bases of teeth, as well as cusps, smooth-edged. odontas f is Yo'^l&v, 1908. 



Indian Ocean. ^ 



3b. Edges of bases of upper teeth at least wavy, irregularly serrate, or denticulate. 



4a. Bases of upper teeth with wavy or irregularly serrate edges, those of lower 



teeth smooth; distance between outer ends of nostrils only about % as great 



as breadth of mouth. brevirostris Poey, 1868, p. 3 lO. 



4b. Bases of some of the teeth, upper or lower, with one strong denticle on the 



outer side;' distance between outer ends of nostrils equal to breadth of mouth. 



acutidens'RxvpT^tW, 1835. 



Tropical Indian Ocean, in- 

 cluding Red Sea (type local- 

 ity) and Arabian Gulf, India 

 and Indo-China, Torres Strait, 

 Micronesia; perhaps Philip- 

 pines.* 



1. Beebe and Tee-Van (Zoologica, N. Y., 26, 1941 : 105) have pointed out that the two specimens on which Jordan 

 and Gilbert's (Proc. U.S. nat. Mus., 5, 1882: 102) original account of fronto was based represented two different 

 species: one with narrow-cusped, broad-based teeth and with the second dorsal nearly as large as the first; the 

 other with small second dorsal and serrate teeth. The second of these was obviously a Carc/iarhinus, perhaps 

 azureus Gilbert and Starks, 1904, but the first, designated by Beebe and Tee-Van as the type of the species fronto, 

 falls in Negafrion as defined here, for Beebe and Tee-Van (Zoologica, N. Y., 26, 1941 : 106) found the teeth 

 of another specimen to be smooth-edged, except where "nicked by some external agency," this last explaining 

 Jordan and Gilbert's original account of them as appearing minutely serrulated under a lens. 



2. Fowler (Bull. U.S. nat. Mus., 100 [13], 1941 : 194) recently has relegated this species to the synonymy of Triae- 

 nodon obesus Ruppell, 1835. But in his original account of it (Proc. Acad. nat. Sci. Philad., 60, 1908: 63) he stated 

 that the teeth are not only slender, erect and smooth-edged, but without basal cusps, and he so pictures them, 

 whereas those of Triaenodon have one or two lateral cusps on each side of the longer median cusp, this being a 

 family characteristic. 



3. According to Mijller and Henle (Plagiost., 1841 : 33) it was the lower teeth that were denticulate at the base in 

 the specimen (probably the type) that they examined and for which they gave measurements. However, if the 

 Afrionodon silakaiensis of Herre, 1934 (Herre, Philippine Exped. Fish., 193 i : 11), is identical with acutidens, 

 as it appears to be, the upper teeth may be so armed. 



4. That is, if silakaiensis Herre, 1934, is identical with acutidens; see footnote 3, p. 309. 



