182 BULLETIN 10 0, TtNITED STATES NATIONAL MUSEUM 



length; interorbital about 2% in head, nearly level. Gill openings 

 small, equidistant, last above pectoral. 



Scales small, tridentate, median point longest. 



First dorsal origin midway between pectoral and ventral origins, 

 front fin edge 1% in head; second dorsal begins behind anal base, 

 length 2% in head ; anal length 21/3 ; least depth of caudal peduncle 

 4% ; pectoral 1%, not quite reaching opposite first dorsal origin, width 

 2 in its length ; ventral length 3 in head ; caudal 2% in rest of body, 

 subcaudal 3 in caudal or l^/^ in head. 



Gray-brown, edges of fins paler. Length, 305 mm, (Miiller and 

 Henle.) 



Red Sea, Mauritius. Garman's specimen vv'as 433 mm. 



Genus HEMIGALEUS Bleeker 



Hemigalcns Bleeker. Verb. Batav. Genootsch. (Plagiost.), vol. 24, p. 45, 1852. 

 (Type, Hemigalcns microstoma Bleeker, designated by Jordan, Genera of 

 Fishes, pt. 2, p. 250, 1919.) 



Chaenogalens Gill, Ann. Lyceum Nat. Hist. New York, vol. 7, p 411, 1862. 

 (Type, Hemigaleus macrostoma Bleeker.) 



Negogaleus Whitley, Australian Zoologist, vol. 6, p. 334, 1931. (Type, Hemi- 

 galeus microstoma Bleeker.) 



Body slender, elongated. Head depressed, flattened below. Snout 

 rounded or tapering. Eye witli nictitating membrane. Mouth with 

 distinct labial folds. Teeth unlike in two jaws; upper inclined, 

 with denticles on basal part of outer edge; lower more erect, with 

 narrow cusp on wide base, without denticles. Spiracles small. 

 First dorsal opposite space between pectorals and ventrals. Tail 

 with prominent subcaudal lobe, notch beliind subcaudal; caudal 

 pits present. 



Small sharks, mostly from the Western Pacific and tropical Indian 

 Ocean. Known by their distinct though small spiracles, labial folds, 

 dentition and distinct caudal pits, also the intestine with few trans- 

 verse turns to spiral valve. 



ANALYSIS OF SPECIES 



a \ Chaenogaleus. Snout tapering, rather pointed ; mouth cleft nearly as long 

 as preoral. 



b\ Caudal less than interdorsal space machlani 



b". Caudal equals interdorsal space macrostoma 



?>^ Caudal 1% in interdorsal space balfouri 



«'. Hemigaleus. Snout broadly rounded ; mouth cleft 2% in preoral ; caudal 

 equals interdorsal space microstoma 



Subgenus Chaenogaleus Gill 



HEMIGALEUS MACHLANI Herre 



Hemigaleus machlani Hev.re, Philippine Journ. Sci., vol. 40, p. 231, 1929 (type 

 locality: Jolo, Sulu Province, Philippines). — Roxas and Martin, Dept. Agr. 

 Comm. Manila Techn. Bull. 6, p. 14, 1937 (reference). 



