374 THE PLAGIOSTOMIA. 



Disciforrn^ subcircular; pectorals meeting in front. No rostral cartilage. 

 Mouth transverse, waved. Teeth tessellated, flattened, rhomboid. Spiracles 

 large, close behind the eyes. Scales tubercular, with broad rounded to poly- 

 gonal bases, varying in shapes, sizes, and numbers with age. Head rather 

 prominent. No dorsal fin. Margins and angles of pectorals rounded. Ven- 

 trals short, broad. Tail long, slender, tapering, without a spine or fins other 

 than a narrow cutaneous subcaudal at some stages. 



Rhachinotus africanus. 



i2aio afncana Schneider, 1801, Bloch Ichth.; p. 367, no. 23. 



Raia asperrima Schneider, 1801, Bloch Ichth., p. 367, no. 24. 



Gymnura asperrima Muller & Henle, 1837, Sitzb. Akad. wiss. Berlin, p. 117. 



Urogymnus asperrimus Muller & Henle, 1837, Wiegm. arch., p. 437; 1838, Charlesworth's mag., 2, 



p. 90; DuMERiL, 1865, Elasm., p. 580; Gunth., 1870, Cat. fishes Brit, mus., 8, p. 571; Klun- 



zinger, 1871. Syn. fische, 2, p. 244; Day, 1878, Ind. fishes, p. 736, pi. 195, f. 1; Annandale. 1909, 



Mem. Ind. mus., 2, p. 37, pi. 3, f. 8, pi. 7, f. 2. 

 Anacanthus a/ricanus Mxjller & Henle, 1841, Plagios., p. 157, no. 1. 

 Anacanthus asperrimus MUller & Henle, 1841, Plagios., p. 157, no. 2, pi. 60, f. 5-7. 

 Rhachinotus africanus T. Cantor, 1849, Malay, fishes, p. 422; Bleeker, 1853, Nat. tijds. Ned. Ind., 4, 



p. 514. 

 Urogymnus africanus Dumeril, 1865, Elasm., p. 581. 

 Urogymnus rhombeus Klunzinger, 1871, Syn. fische, 2, p. 243. 

 Urogymnus laevior Annandale, 1909, Mem. Ind. mus., 2, p. 37. 



Disk suboval, more pointed backward, with a slight prominence at end of 

 snout. Anterior nasal valves confluent, fringed posteriorly. Mouth waved, 

 palatal velum fringed, three to five papillae at the bottom. Teeth blunt, broader 

 than long, in about forty-eight rows on the jaw of a specimen over twenty inches 

 in length of body. Scales tubercular, unequal, more or less striated, with rounded 

 bases where not in contact, with polygonal bases where crowded and with cusps 

 short to long, acute, blunt, or rounded to depressed and shovel-shaped. One 

 specimen shows that the cusps over body, head, and basal portion of tail, are 

 irregularly of two forms; one short depressed shovel- or horse-shoe shaped with 

 an excavation toward the base, the other, on the larger tubercles, mt)re conical 

 and erect. In a wide area around the edge of the disk, where the scales are not 

 in contact, only the latter appear. The depressed cusps are directed from either 

 side toward the median line of the back; as the line is approached they turn more 

 backward. Ventrals well covered by the pectorals. Tail nearly twice the length 

 of the body, with or without a narrow fold below according to age. 



Yellowish to whitish on the tubercles; skin dark brown where exposed. 



Indian Ocean; East Indies. 



