250—10 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
As the fossil is larger than any of the existing species of Chrysichthys (and 
Clarotes\ it may be regarded as distinct, and provisionally named Chrysichthys (?) 
theobaldi. 
Genus II. Macrones, Dum^ril.^ 
Characters. — Teeth on the palate in a continuous band; no moveable lateral 
teeth ; upper jaw the longer ; skull long ; median portion of the upper surface of 
the cranial bones covered with a radiate sculpture. 
Distribution. — The genus is confined to Asia, nineteen species being enumerated 
by Dr. Gunther^ ; it is divided into two groups from the characters of the fins, one 
of those groups being subdivided according to the presence or absence of a separate 
interneural shield on the nape. 
A. A separate interneural shield on the nape. 
Species. Macrones aor (Buch. Hamilton®). 
Syn. Pimelodus aor, Buch. Hamilton.^ 
Bagrus aor, Cuvier and Vallenciennes.® 
(From the Biwalihs). 
History of fossil form. — The fossil specimen identified with this species is 
described for the first time ; it was obtained from the Siwalik Hills, and on the 
death of Dr. Falconer was ^^resented by his brother to the British Museum. 
Skull. — The above-mentioned specimen is represented of two-thirds the natural 
size in plate XXXVI. fig. 5 ; it comprises the entire skull, and the greater portion 
of the bones of the humeral arch in very perfect preservation, although on the left 
side the gill-cover has been crushed in beneath the cranium. The villiform 
teeth on the premaxillse are distinctly visible, but the palatal teeth are concealed 
by the mandible and matrix. The upper jaw overlaps the lower, and tlie position 
of the widely separated anterior and posterior nares (na, no) is clearly indicated. 
Compared with a full-grown stuffed specimen of Macrones aor in the British 
Museum, measuring nearly three feet in length, the fossil agrees so closely that 
there can be little, if any, doubt as to its specific identity. It agrees exactlj^ with the 
recent skull in size, and, allowing for a small fracture on the lateral borders of the 
fronto-parietal region, and the loss of the extremity of the supraoccipital process, 
absolutely no difference can be detected in respect of form and structure. The 
skull of the existing Indian Macrones lamarii^ (the only other member of the present 
sub-group) is relatively longer and narrower, and has the cranial sculpture some- 
what finer. 
Distribution. — The existing form appears to be distributed over Burma and the 
1 “ Ichthyologie Analytique,” p. 484 (1856). 2 “ Catalogue of Fishes,” vol. V. pp. 74-84 (1864). 
3 “ Fishes of the Ganges,” p. 205 (1822). Pimelodus. 4 Loc. cit. 
5 “Hist. Nat- d. Poissons,” vol. XIV. p. 405 (1839). 
6 Day (“ Fishes of India”) identifies this species with M. seenghala (Sykes), and adopts the latter name. Gunther 
(“ Catalogue of Fishes,” vol. V. p. 78) considered M. seenghala as a synonym of M. aor. 
