PTEROMYLAEUS. 137 



length, the outer angle is less sharp than on A. milvus, the tip is more rounded, 

 and the hind angle is somewhat sharper. Ventrals about twice as long as wide, 

 outer angle rounded, hind margin a broad curve from the outer angle to the end 

 of the base. Dorsal small, with a short free inner margin behind the end of the 

 base, one third of the base behind the ends of the ventrals, origin nearly opposite 

 ends of ventral bases. Tail three times the length of the body, or more; no 

 caudal spine. No orbital horn in most cases. Skin somewhat roughened in 

 old specimens. 



Back brown, with five or six narrow bands of lighter, bluish, disappearing 

 with age; lower surfaces white outer margins of pectorals brownish. 



India; East Indies; Japan. 



Aetomylaeus vespertilio. 



Myliobaiis milvus T. Cantor, IS 10, Malay, fishes, p. 433. 



Myliobatis vespertilio Bi.eeker, 1852, Verh. Bat. gen., 24, Plagios., p. 85; Du.meril, 1865, Elas., p. 636; 



Gunth., 1870, Cat. fishes Brit, mus, 8, p. 490. 

 Aetomylaeus vespertilio Gar.man, 190S, Bull. M. C. Z., 51, p. 253. 



Disk nearly twice as broad as long. Teeth in the middle row six times as 

 broad as long; upper pavement as broad as long, lower longer than broad. 

 Nasal valves confluent, flap with rounded angles, little notched in the middle. 

 Pectorals convex in front, concave behind, acute in the outer angle. Dorsal 

 origin behind the ends of the ventral bases, fin not extending to ends of the 

 ventrals. No horn on the orbit. No caudal spine. Skin smooth. An in- 

 dividual measured had a width of 19, a length from snout to vent of 7|, and 

 a length of tail of 46i inches. 



Fawn color, with anastomosing black lines arranged transversely on the 

 anterior half of the disk so that the spaces between resemble broad transverse 

 bands ; elsewhere the lines form an open net-work ; front margin of pectorals and 

 dorsal without black meshes. Tail near the base brownish with faint rings of 

 blackish, otherwise black. Ventral surfaces white. 



Batavia ; Penang. 



Pteromylaetjs. 



This genus resembles Aetobatus somewhat closely in general appearance 

 and in structure but differs greatly in dentition. Compared with Myliobatis 

 the head is more elongate, and more narrow forward and in the snout, the 

 pectoral fins are more falciform and are not continuous with the rostral fins at 



