588 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 115 



This genus is at least superficially closest to Rhizoprionodon. 

 A single species distributed from the southwest coast of Africa to 

 the Red Sea, India, the Philippines, Dutch East Indies, and Australia. 



Loxodon macrorhinus Miiller and Henle 



Figure 4; Plate 1a 



Loxodon macrorhinus Miiller and Henle, 1841, Systematische Beschreibung der 



Plagiostomen, p. 61, pi. 25 (embryo, locality unknown). 

 Carcharias (Scoliodon) dumerili Bleeker, 1856, Act. Soc. Sci. Indo-Neerl., vol. I, 



p. 70 (Amboina). 

 Scoliodon jordani Ogilby, 1908, Proc. Roy. Soc. Queensland, vol. 21, p. 88 



(outer Caloundra Bank, Queensland). 

 Scoliodon affinis Ogilby, 1912, Mem. Queensland Mus.,vol. l,p. 29 (Noosa Head, 



south Queensland). 

 Scoliodon ceylonensis Setna and Sarangdhar, 1946, Proc. Nat. Inst. Sci. India, 



vol. 12, no. 5, p. 252 (Bombay waters; no type material listed). 



Diagnosis. — Distinctive characters are those of the genus (q.v.). 



Description (see also table 6). — Precaudal vertebrae 77-106 (table 

 7), centra in posterior monospondylous region elongate (plate 

 1a); caudal vertebrae 71-86; total vertebrae 148-191; upper teeth 

 12-1-12 to 13-1-14; lower teeth 12-12 to 14-14 (higher, or lower, 

 counts in upper and lower jaws correlated). 



Denticles imbricate, 3- to 5-ridged and 3- to 4-toothed. 



Color of preserved specimens: brown to gray brown above, pale 

 below. Pectoral and pelvic fins pale-edged; caudal either pale-edged 

 or with a narrow black margin; first dorsal dusky distally. The 

 distal portions of the claspers of adult males paler than remainder. 



A low, short interdorsal ridge is sometimes present close to the 

 first dorsal fin (e.g., one specimen from the PhiHppines had it, another 

 did not). 



The largest immature male seen, from Misol Island, was 660 mm. 

 t.l., and had a clasper length equal to 2.4 percent of the t.l. The 

 smallest mature male, from the PhiHppines, was 745 mm. t.l. and 

 had a clasper length equal to 7.2 percent of the t.l. The skin of a male 

 approximately 900 mm. t.l. from Kenya, Africa, had a clasper length 

 of 63.5 mm., ca, 7.3 percent of t.l. 



The largest embryo seen was 421 mm. t.l. and the smallest non- 

 embryo specimen was 429 mm. t.l. 



The cusps of the teeth of adult males may be slightly more erect 

 than those of females, but the difference is not striking. The cusps 

 are smooth, even in large specimens. 



Distribution (see "Material"). — The presence of this species in 

 India is based on Setna and Sarangdhar (1950, as Scoliodon acutus). 



