Davis— On the Fossil Fishes of the Chalk of Mount Lebanon. 565 
Osmeroides dubius, Davis. 
(Bl xxxn, fis. 45) 
The body of this fish is short and stout. The length, from the snout to the 
base of the tail, is 2°6 inches, of which the head occupies 0:7 of an inch. The 
tail is also 0:7 of an inch in length. The height immediately behind the head is 
0-8 of an inch; at the base of the tail it is 0-45 of an inch. The dorsal fin 
occupies a position slightly anterior to that of the ventrals. 
The head occupies rather less than one-fourth the length of the body. Post- 
orbitally the height is equal to the length. The orbit occupies a superior position 
about midway in the length of the head; the infra-orbital bones are strong and 
well developed. The maxilla extends behind the orbit, 0-45 of an inch in length ; 
it is 0°05 of an inch deep at its articulating extremity, and becomes thinner 
towards the snout; the pre-maxillary is unfortunately displaced. The mandible 
is strong, and also converges anteriorly. No trace of teeth can be distinguished. 
The branchiostegal rays, eight in number, are fine and small, 0:2 of an inch in 
length, and curved backwards. The opercular plates are large, smooth, and 
enamelled. 
The spinal column is formed of sixty vertebrae, seventeen of which are 
included in the caudal region. They are much higher than long, especially those 
situated near the caudal extremity. The ribs and anterior neural spines are not 
defined, being hidden by the scales. The neural and hemal spinous processes of 
the posterior vertebree are short and thick. Interspinous bones, seven of which 
are visible, support the dorsal fin; others are also indicated in connexion with the 
anal. 
The dorsal fin is situated on the anterior portion of the body; itis 0°65 of an 
inch behind the head, and 1 inch in advance of the caudal fin; its base occupies 
0-4 of an inch, and it consists of twelve rays, the anterior ones 0°8 of an inch in 
length. The anal fin is 0°2 of an inch in advance of the caudal; in the specimen 
described it unfortunately happens that the opposite matrix has carried away a 
portion of the fin, and only a fragment remains. The caudal fin is broad at the 
base, and short; the outer rays are 0°7 of an inch in length, the median ones not 
more than half that length, so that the tail is forked; the outer rays are supported 
by ten to twelve rudimentary imbricating rays. 
Of the paired fins, the pectorals are not represented; the ventrals are midway 
betwixt the head and the anal fin; they occupy a more posterior position than the 
dorsal fin. Each ventral fin is supported by seven rays, the length of which 
cannot be accurately determined. 
The body is enveloped in closely imbricating scales; the exposed surface is 
circular and smooth, covered with brown enamel. The lateral surface of the 
TRANS. ROY. DUB. SOC., N.S. VOL. ILI. 4H 
