256—16 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
Gtenus. Non. det. 
Cyprinodont, gen. non det. Skull ; from 
the Siwalik Hills. Dublin Museum 
(No. C. 92). The smaller figure shows 
one of the scales enlarged. 
[From the SuvaUks). 
History. — The single specimen forming the subject of the present notice is 
preserved in the Museum of Science and Art, Dublin ; and was collected in the 
Siwaliks by Grenerals Sir W. E. Baker and Sir H. M. Durand.^ 
Skull. — The above-mentioned specimen, which is figured of the natural size in 
the accompanying woodcut, comprises the nearly 
entire skull. Both nostrils and the greater part of 
the right orbit are clearly shown ; while the oper- 
cular bones of the same side are but little injured. 
Teeth (though not visible in the figure) are present 
in both* jaws, and appear to be arranged in a single 
series : they are all more or less broken, but those 
of the lower jaw appear to have been incisor-like. 
The nostrils are subterminal, the cleft of the mouth 
is small, the mandible short, the snout short and 
vaulted, and the scales rather large. It cannot be 
determined whether the mandibular rami were 
anchylosed. The scales show a radiate sculpture ; 
and the specimen indicates a fish of from eight to 
ten inches in length. 
Affinities. — The size and form of the operculars seem to indicate that the 
specimen belongs to a fish allied to the carps ; and the presence of scales on the 
head differentiates it from the Gyprinidce^ Gharaciniidce, and Heteropyfjiidce. In this 
respect, as well as in the presence of teeth in the jaws, it agrees with the Cyprion- 
dontidce., to which it may be provisionally referred. The very small size of all the 
existing species of Gyprinodon renders it improbable that the fossil belongs to that 
genus ; and the vaulting of the snout distinguishes it from the living Indian genus 
Haplochilus. Beyond this its imperfect nature renders it inexpedient to go, but the 
specimen is interesting as indicating a Siwalik fish apparently different from any 
existing Indian species. 
Order III. PLECTOONATHI. 
Family. DIODONTID^.'^ 
( 'liaracters. — Bones of the upper and lower jaws confluent, forming a trenchant 
edentulous beak, with or without median suture. 
Gtenus. DIODON, Linn.® 
Gharacters . — Jaws without median suture ; a compound palatal dental plate. 
Distribution. — The genus is represented at the present day by a large number of 
1 Vide ‘ Trans. R. Dublin Soc.’ ser. 2. vol. III. p. 70 (1884). 
2 The name Gymnodontes or Gymnodontidce is usually applied to this family, hut as it is not taken from a generic name it 
is inapplicable. 3 “ Syst. Nat.” ed. 12. vol. I. p. 412 (1766). 
