Genus OSMEROIDES9 Agassiz 
[Poiss. Foss. vol. V. pt. ii. 1844, p. 103.] 
Svn. Rhabdolepis, W. von der Marck (non Troscliel, 1857), Palaeontogr. 
vol. xi. 1863, p. 26. 
Holcolepis, W. von der Marck, ihid. vol. xv. 1868, p. 278. 
Head and trunk not much laterally compressed, and abdomen 
flattened. Parietal bones in contact in the median line; mandible 
a little prominent, and gape not extending behind the eye; two 
supramaxillary bones; margin of the jaws and some inner bones 
with clusters of minute bluntly-pointed teeth, sometimes perhaps 
tritoral. Branchiostegal rays about 20 in number, about five of 
the uppermost and broadest supported by the epihyal. Yertebrm 
between 50 and 70 in number, about 20 being caudal; the centra 
not longer than deep, aU slightly constricted and marked with 
small irregular longitudinal ridges. No 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, marked in their covered portion with a few 
radiating grooves terminating 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. 
The generic name Osmeraides was originally given by Agassiz to 
some fishes from the Cretaceous of Westphalia catalogued below 
in the family Scopelidse {Sardinioides monasteri). When it was 
afterwards applied to fossils discovered by Dr. Mantell in the 
English Chalk, Agassiz expressly stated that the determination of 
generic identity w^as uncertain and provisional. In course of time, 
however, the name has become universally recognised as belonging 
to the English specimens, and least confusion will be caused in 
established nomenclature if Osmeroides leiuesiensis be regarded as 
the type species. 
Osmeroides lewesiensis (Mantell). 
[Text-figure 2.] 
1822. Sahno lewesiensis, G. A. Mantell, Foss. South Downs, p. 235, 
pi. xxxiii. fig. 12, pi. xxxiv. fig. 3, pi. xl. fig. 1. 
1 This name was first published, without definition, by Agassiz, Neues Jahrb. 
1834, p. 305. 
