736 PLAGIOSTOMATA— BATOIDEI. 



Family, V-TRYGONIDJE. 



Disk wide : the pectorals are continued to the extremity of the snout where they become confluent. 

 Tail long and slender without any lateral folds. Vertical fins, if present, imperfectly developed, or instead 

 they may be modified into a serrated spine. 



The forms with armed tails occasion exceedingly dangerous injuries, not only due to their jagged 

 nature, but apparently also to the presence o£ some irritating foreign substance which becomes carried into 

 the wound. 



Geographical distribution'. — Tropical and temperate seas. 



SYNOPSIS OF GENERA. 



1. UrogymMus—Tail long and spineless. Body densely covered with tubercles, p. 736. 



2. Trygon — Tail long, armed with a serrated spine. Teeth flattened, p. 736. 



3. TxniAira — Tail long, armed with a serrated spine, and having a broad lower cutaneous fold continued 

 to its termination, p. 740. 



4. Pteroplatea — Body very broad, tail very short and armed with a serrated spine. Teeth with from 

 one to three cusps, p. 741. 



Genus, 1 — TJrogtmnus, Miiller and Senle. 



Anacanthus, Ehren. : Bhachinotus, Cantor. 



Dish sub-circular : tail long and distinct, destitute of any spine, but witJi a narrow inferior fold : pectorals 

 united anteriorly. Teeth flattened. Body covered with osseous tubercles, amongst which are sharp conical spines. 



Geographical distribution. — Erom the Red Sea and East coast of Africa, throughout the seas of India to 

 the Malay Archipelago. 



TJrogymnus asperrimus, Plate CXCV, fig. 1. 



Baja asperrima and ? Africana, Bl. Schn. p. 367. 



Anacanthus asperrimus and ? Africana, Miill. and Henle, Plagios. p. 157. 



Bhachinotus Africamus, Cantor, Catal. Mai. Pish. p. 422 ; Bleeker, Nat. Tyds. Ned. Ind. 1863, iv, p. 64. 

 TJrogymnus asperrimus, and Africanus, Gray, Cat. Ohond. p. 116 ; Dumeril, Hist. Nat. Poiss. i, pp. 680, 

 681 ; Giinther, Catal. viii, p. 472 ; Klunz. Fische Roth. Meer. 1871, p. 64. 



Moollan tirihi. Tarn. 



Disk nearly as wide as long : snout scarcely projecting. Body densely covered with small heart-shaped 

 scales, between which are numerous thorns which are generally erect, and are continued posteriorly to the first 

 fifth of the tail, where they cease. On the pectoral fins are numerous small conical spines, irrespective of those 

 over the body amongst the tubercles. Colours — greenish above, white beneath. 



A fine example, 2 feet across the disk, exists in the Madras Museum.* 



Habitat. — Red Sea, East coast of Africa, seas of India to the Malay Archipelago. 



Genus, 2 — Tetgon, Adanson. 



Eimantura, Himitrygon and Hypolophus, Miill. and Henle : Paratrygon, Dumeril. 



Disk oval or rhomboidal : tail elongated and tapering. Nasal valves coalescent, forming a quadrangular 

 flap. Teeth flattened or with a central point or transverse ridge. Pectoral fins united anteriorly: tail destitute of 

 a fin, or if with a cutaneous fold, such does not extend to its extremity : it is armed superiorly with one or two 

 lanceolate spines serrated on both sides. Body smooth or with tubercles. 



In this Genus the colours in individuals of the same species are subject to considerable variation, and 

 this not entirely due to age. The character of the tubercles and their extent have also been (as I think 

 erroneously) employed to characterize some species, thus one, Trygon chindrahee (Cuv.) Bleeker or T. nuda, 

 Giinther, is a form without tubercles or spines, except on the tail. T. polylepis, Bleeker, has small tubercles 

 in the interorbital space, a narrow band along the back with a few indistinct enlarged ones, but none on the tail. 

 T. walga, Miill. and Henle, has the interorbital space and back covered with small tubercles, but no larger ones 

 in the median line, but a series of short spines between the root of the tail and the larger spine. Now all 



* I must here remark that, when referring to the specimens of fish in the Madras Museum, I allude to what were there in 

 1873, as since then the Curator (under, I presume, orders from Government) has given away some of the finest examples. 



