730 PLAGIOSTOMATA— BATOIDEI. 



Family, II— RHINOBATID^. 



The disk slightly dilated laterally: the rayed portion of the pectoral fin not continued on to the snout. 

 Tail thickened, moderately elongated, and with a longitudinal fold along either side. Two well-developed 

 dorsal likewise a caudal fin. No electric organs. 



These fishes are very destructive amongst marine Crustacea and molluscs : and are said to live in large 

 droves. Owing to the great injury done by them to the beds of pearl oysters at Ceylon, it was proposed to 

 enclose such with stakes to prevent their ingress. 



Geographical distribution. — Tropical and temperate seas. 



SYNOPSIS OP INDIAN GENERA. 



1. Bhi/nchnhatus. Two dorsal fins, the anterior opposite the ventrals, p. 730. 



2. Mhinohatus. Two dorsal fins, the anterior situated far behind the ventrals, p. 731. 



Genus, 1 — RHYNcnoBATUS, iluUer and Henle. 



Rhina, sp. and Bhinohatus, sp. Bl. Schn. : Rhamphohatis, Gill. 



Body depressed and elongated. G-ill-openings inferior, narrow, and internal to the base of the pectoral fin. 

 Spiracles wide and behind the eyes, tvhich latter have no nictitating membrane : snout rather elongated and acute : 

 nostrils inferior, oblique, wide slits. Teeth obtuse, ridged : the dentary plate having an undulated surface. Dorsal 

 fins spineless, the first oj^posite the ventrals : front edge of pectoral free, not extending to the head: caudal with a 

 well-marked lower lobe. 



Geographical distribution. — From the Red Sea and East coast of Africa through the seas of India to the 

 Malay Archipelago and China. 



SYNOPSIS OF SPECIES. 



1. Eliynchobntus ancylostomus. Snout broad, having a semi-circular outline. Rows of large tubercles and 

 spines on head and trunk. Brown. From the East coast of Africa through seas of India to the Malay Archipelago 

 and China. 



2. lihynchobatns Djeddensis. Snout elongated : few tubercles or spines on head or body. A black 

 shoulder spots and numerous white spots on upper surface. Red Sea to the Malay Ai-chipelago, and beyond. 



1. Rhynchobatus ancylostomus, Plate CXCIIl, fig. 3. 



BJtina ancylostomus, Bl. Schn. p. 3.52, t. Ixxii ; Gray and Hardwicke, 111. Ind. Zool. ; Agassiz, Poiss. 

 Foss. iii, p. 82, t. H. f. 3 and 4 ; Richards. Ich. China, p. 195 ; Miill. and Henle, Plagiost. p. ilO ; Cantor, 

 Catal. Mai. Fish. p. 409 ; Bleeker, Bong. p. 80 and Plagiost. p. 56 ; Jerdon, M. J. L. and Sc. 1851, p. 148. 



Rhina cyclostomus, Swainson, Fishes, ii, p. 322. 



Rhamphobatis ancylostomus. Gill, Ann. Lye. Nat. Hist. New York, 18G1, vii, p. 408. 



Rhynchobatus ancylostomus, Giiuther, Catal. viii, p. 440. 



Manu ulava, " mud skate," or Nulla dindi, Tel. 



Snout very broad with a semi-circular outline. It has longitudinal rows of tubercles, one on either side 

 of the head above the eyes continued on to the shoulders, and a median one along the back, with two short 

 lateral ones between this last and the pectoral tin : a few round the front edge of the eye and below the spiracle. 

 Teeth — 77/75. Twenty-two vertical rows in the centre of the upper and twenty-seven in the centre of the lower 

 jaw. The dental surface deeply undulated, with one large median and a smaller lateral elevation in the lower jaw 

 and with corresponding emai-ginations in the upper. The teeth are largest on the summit of each elevation : 

 all are obtusely rounded with several longitudinal ridges across each. Cohnirs — of a dull brown, ligliter 

 beneath : the body and sometimes the fins covered with whitish spots : occasionally some tortaous black lines. 



Habitat. — i^rom the East coast of Africa through the seas of India to the Malay Archipelago and China. 

 The figure is taken from an example sent by Dr. Jerdon from Madras to the British Museum : its length was 

 ti ft. 10 in. ; and inside it were found the remains of great numbers of Crustacea of many kinds. The natives 

 assert that it swims slowly just above the bottom of the sea not far from the shore, picking up what it finds. 



2. Rhynchobatus Djeddensis, Plate CXCII, fig. 1. 

 Rhinobafns, Duhamel, Pesches, ii, pi. xv, figs. 1 and 2. 

 Raja Djiddensis, Forsk. Descr. Anim. p. 18. 



