BRITISH FOSSILS. 



Decade YIIL Plate IX. 



OXTGNATHUS. Gen. Nov. 



[Gaaas OX^GXATHUS. Egsrtox. (Sub-kingdom Vertebrata. Class Pisces. 

 Order Goniolepidoti. Family Sauroidei. Sub-family Sauroidei homocerci. 1st Group. 

 Tail forked.) Body elongated ; head pointed ; jaws furnished with numerous small in- 

 curved teeth, intermixed with larger ones ; scales thick, small, rhomboidal, and covered 

 with siauous longitudinal furrows ; pectoral fins short and broad ; ventral fins large ; 

 anal fin small.] 



Oxygnathus ornatus^ Sp. Nov. 



Description. — This fish has so many striking peculiarities, that it 

 has been necessary to create a new generic title for its designation. 

 The slender lanceolate form of the body resembles some species of 

 Eugnathus, the characters of the teeth and jaws approach those of 

 SauTopsis, while the peculiar ornamentation of the scales can only 

 be compared to thai) found in the heterocerque genus, Acrolepis. 

 The combination of these characters, and the addition of others not 

 found in the above cited genera, establish the propriety of selecting 

 for this form a new generic appellation. The specimen measures 

 9^ inches, from the snout to the base of the caudal fin, of which the 

 head occupies 3 inches. The greatest depth of the body was probably 

 not more than 2 inches, but the attitude of the fish is such that this 

 measurement cannot be ascertained with precision. This, however, 

 is clear, that the deepest part was immediately behind the nape, 

 from which point the body gradually tapers to the tail. The dorsal 

 and caudal fins are both absent. The form of the head is more 

 pointed than in any of the Sauroid genera, except those with elon- 

 gated muzzles, such as Aspidorhynchus, Belonostomus, and Saur- 

 ichthys. In consequence of the extreme tenuity of the bones of the 

 head few are preserved entire, with the exception of the dentigerous 

 bones, and the hyoid and branchiostegous apparatus. These are 

 all covered with a surface ornament, composed of fine vermicular 

 plaits of enamel, arranged for the most part in longitudinal direc- 

 [viii. ix.] 8 K 



