470 Davis—On the Fossil Fishes of the Chalk of Mount Lebanon. 
chalk of Hakel, and four from the soft chalk. Cyclobatis oligodactylus, de- 
scribed by Sir P. Egerton, was from the hard chalk of Djebail: it has since 
been found at Hakel. 
(A)—SELACHOIDEI—SHARKS. 
F amily. NOTIDANIDZ. 
Genus. Notidanus. CuviER. 
Dentition unequal in the jaws. In the upper jaw one or two pairs of awl- 
shaped teeth, the following six being broader, and provided with several cusps, one 
of which is much the strongest. Lower jaw with six large comb-like teeth on each 
side, beside the smaller posterior teeth. Spiracles small on the side of the neck ; 
no pit at the root of the caudal fin; gill-openings wide, six or seven in number 
(Giinther) ; one dorsal fin opposite to the space between the ventral and anal fins. 
Notidanus gracilis, Davis. 
(Pl. xrv., figs. 1, 1a.) 
Ventral surface exposed; head with mouth; under surface of pectorals and 
ventrals; anal and caudal fins. Body and fins covered with a thick skin, coated 
with minute, rounded tubercles: the skin more or less wrinkled and furrowed. 
Length, 13 inches; diameter behind pectorals, 1:6 inches, diminishing 
posteriorly to ‘6 at the base of the tail. Head, 2°5 inches; tail, 3°5 inches 
in length; anal 2 inches in front of caudal. The ventrals nearer to the anal 
than to the pectorals. 
Head, only under surface exposed; snout extends 0:7 in. beyond the mouth. 
Mouth, large; deeply arched. The jaws extend a further distance back- 
wards than the diameter at their base; strong and robust. Teeth, lower jaw, 
0:3 inches long; strong flat base, from which rise a series of five denticles, 
anterior one largest, having a length of 0:1 inch, succeeding ones diminishing 
posteriorly, as in the recent Notidanus; the edges sharp and free from serration. 
Teeth, apparently from the upper jaws, lie scattered about; they are conical, 
compressed antero-posteriorly, with sharp edges, and a somewhat broad base, 
either without lateral denticles, or in some instances apparently possessing one 
on each side. The median cusp is slightly, if at all, longer than the anterior 
one of the teeth of the lower jaw. 
Vertebral column consists of about 145 vertebra, of which 115 are preserved 
in the specimen, and the remainder it is calculated would be required to complete 
the part of the tail which is missing. The vertebre are largest near the head, 
