L14 FOSSIL PISHES OF THE ENGLISH CHALK. 



enlarged scale at the base of the paired fins; dorsal fin never much longer than 

 deep, opposite or nearly opposite the pelvic pair; anal smaller than the dorsal fin; 

 caudal fin forked; no fin-rays excessively elongated. Scales often ornamented in 

 their exposed portion with delicate radiating lines of minute tubercles ; very finely 

 granulated in their covered portion and marked with a few radiating grooves 

 which terminate in notches at the anterior truncated margin ; hinder margin not 

 serrated. Course of lateral line indicated by a feeble ridge and a notch in the 

 hinder border of most of the scales. 



Type Species.— The generic name Osmeroides (first published without definition in 

 Neues Jahrb., 1834, p. 305) was originally given by Agassiz to some Scopeloid fishes 

 from the Cretaceous of Westphalia, which are now generally known as Sa,rdinioides. 

 When it was afterwards applied to fossils discovered by Mantell in the English 

 Chalk, Agassiz expressly stated that the determination of generic identity was 

 uncertain and provisional. In course of time, how r ever, the name has become 

 universally recognised as belonging to the English specimens, and Osmeroides 

 leioesiensis must be regarded as the type species. 



1. Osmeroides lewesiensis (Mantell). Plate XXIII, figs. 1 — 8; Text-fignre 38. 



1822. Salmo lewesiensis, G. A. Mantell, Foss. South Downs, p. 235, pi. xxxiii, fig. 12; pi. xxxiv, fig. 



3; pi. xl, fig. 1. 

 1837-44. Osmeroides lewesiensis, L. Agassiz, Poiss. Foss., vol. v, pt. i, p. 14 ; pt. ii, p. 105, pi. lx b, 



figs. 1, 2, 5 — 7 {non figs. 3, 4) ; pi. lx c. 

 1838. Osmeroides mantellii, G. A. Mantell, Wonders Geo!., vol. i, p. 307, fig. 1. 

 1888. Osmeroides lewesiensis, A. S. Woodward, Proc. Geol. Assoc, vol. x, p. 322. 

 1895. Osmeroides lewesiensis, A. S. Woodward, Proc. Zool. Soc, 1894, p. 656, pi. xlii. 

 1901. Osmeroides lewesiensis, A. S. Woodward, Catal. Foss. Fishes B. M., pt. iv, p. 12. 



Type. — Imperfect fish, probably from a Turonian zone ; British Museum. 



Specific Characters. — The type species, attaining a length of about 45 cm. 

 Head Avith opercular apparatus occupying about one quarter of the length to the 

 base of the caudal fin. Length of cranium somewhat exceeding twice its maximum 

 width at the occiput; each parietal bone longer than broad; bones of the hinder 

 half of the cranial roof, cheek-plates, opercular bones, and upper branchiostegal 

 rays ornamented with coarse radiating rugae. Pelvic fins, each with at least 

 eleven rays, opposed to the hinder half of the dorsal ; the small anal fin nearer to 

 the caudal than to the pelvic pair. Exposed area of scales narrow and deep, 

 usually smooth, sometimes ornamented with very fine closely-arranged radiating 

 lines of tubercles. 



Description of Specimens. — The type specimen in the Mantell Collection (no. 

 4294) lacks the greater part of the caudal region, but otherwise displays satisfac- 



