Davis—On the Fossil Fishes of the Chalk of Mount Lebanon. 557 
broad and flat; the scales are thick and strong; and though, unfortunately, the 
spinal column is not known in its entirety, detached vertebre have been identified, 
and indicate by their great height as compared with the length, that they were 
more numerous than those of the other species described by Agassiz, and pro- 
bably numbered as many as those found in the chalk of Mount Lebanon. 
Thus, whilst Osmeroides is, without doubt, closely related to both the Clupeide 
and the Salmonidz, it possesses several features which separate it from these 
families, and necessitate its being considered as occupying an independent 
position. 
Osmeroides megapterus, PIcTET. 
(Pl. xxxm1., figs. 4-6.) 
Osmeroides megapterus. Prcrer, 1850. “‘ Desc. de quelques poissons fossiles du 
Mont Liban.,” p. 27, pl. m1, fig. 3. 
Osmeroides megapterus. Picrer et Humpert, 1866. ‘‘Nouy. rech. sur les poiss. 
foss. du Mt. Liban.,” p. 78. 
Osmeroides megapterus. Fraas, O., 1878. ‘Aus dem Orient. II. Theil. Geolo- 
gische beobachtungen am Libanon,” p. 98. 
The specimen described and figured by M. Pictet is imperfect; the acquisition 
of more perfect specimens, since the publication of his work, enables me to 
supplement the description there given as follows:—The length of the body, 
exclusive of the tail, varies from 4 to 7 inches, of which the head occupies 1-8 
inch in the larger size; the tail is 1°5 inch in length. The height of the 
body at its junction with the head is 1:8 inch, and the peduncle of the tail is 
about half that height. The dorsal fin commences 1:0 inch behind the head, 
and its base extends 0°8 inch. The pectoral fins are inserted immediately behind 
the gill covers, and separated from the ventrals by a distance of 2:0 inches. 
The anal fin is 1°5 inches behind the ventrals, and has a basal length of 0-7 inch, 
and is about half an inch in front of the caudal fin. The caudal is moderately 
cleft and widely expanded. 
The head is as high posteriorly as its length; the snout is wide and large, 
flattened on the upper surface, with a proportionately wide gape; teeth small, 
closely set, and finely pointed. The operculum is 0°8 inch in diameter, with 
well-rounded posterior margin, the anterior one straight on the lower portion, 
but rounding off towards the upper one. The under surface of the head between 
the operculi is occupied by branchiostegal rays, eight in number on each side 
(not seven, as stated by M. Pictet, Op. cdt., p. 28), curved, and about 0-7 of an 
inch in length; the upper surface of the head, above and behind the orbit, is 
covered with thickly enamelled plates. The orbit is not well defined. The 
jaws are long and somewhat slender. 
TRANS, ROY, DUB, SOC., N.S. VOL. III, 4G 
