tgoS.] ,'. . , Records of the Indian Museum. ■ ~_ ' ; lyg 



This was so different from the skull of Ceraioptera that it has 

 been shown in outline in fig 3, pi. x. The cranium of Aetohatis is a 

 box-like structure provided with well-developed orbits, that is to 

 say it is not unlike the type found in many other elasmobranch 

 fishes, but a great contrast to that of Ceratoptera. This difference 

 is so marked that a separate origin for the two divisions of the 

 MyliohatidcB might have to be admitted. In order to demonstrate 

 this, an examination of the skulls of other genera of the family 

 would be necessary. - . 



Fig. 2. — Teeth of D. eregoodoo. FiG. 3. — Teeth of D. thurstoni. 



During a recent visit to Madras I had, through the kindness of 

 Mr. E. Thurston, an opportunity of examining the large rays in the 

 Museum of that city. Among them are two examples of Dicerohatis 

 which clearl}^ belong to separate species. Photographs of these are 

 shown on plate iv. One of them agrees closely with the definition 

 of D. eregoodoo, the species usually found in Indian seas, though by 

 no means commonly. Cantor ^ gives a full description of this fish ; 

 regarding the teeth he writes : '' the teeth are uniformly minute, flat- 

 tened, of a pentagonal shape, with backwards- directed points; the}^ 

 have frequently two or three such points ; they are generally twice 

 broader than long. The upper jaw has 80, the lower jaw 94 rows of 

 teeth." The teeth of the specimen in the Madras Museum has 60 

 rows of teeth in the upper jaw, but in form (text-fig. 2) they agree 

 with Cantor's description ; the teeth of the same species are shown 

 by Dumeril '- in a figure which shows some slight difference. In spite 

 of this the smaller Madras specimen should, I think, be placed in 

 the species D. eregoodoo. The larger specimen is quite different, 

 however; it has twice as many teeth, which are of a different 

 character. As it does not appear to resemble any known species it 

 has been described here. 



Dicerohatis thurstoni, sp. no v. 



Teeth in 140 series in the upper jaw, extending nearly to the 

 angle of the mouth. Each tooth is separated from its neighbours 

 by an interval, and consists of an irregular nodular base bearing 

 from two to four spinous cusps (text-fig. 3). 



1 Catalogue ofJMalayan Fishes, p. 1420. 



2 Hist. Nat. des Poissons, pi. 6, figs. 2 — 5. 



