540 Davis—On the Fossil Fishes of the Chalk of Mount Lebanon. 
bifurcated ; there are eleven or twelve rays in each lobe; they are articulated, 
and divided towards their extremity; a number of rudimentary rays also 
support each of the two lobes. 
The pectoral fins are indicated by an impression only on the lateral surface 
of the body, and the ventrals are altogether absent. The scales are less than 
the tenth of an inch in height ; the surface is minutely striated, and the posterior 
margin circular, with very small crenulations. 
This species is distinguished by its gracefully proportioned form, by the 
opposition of the dorsal and anal fins, and by the large number of the rays 
supporting the dorsal fin, and probably that of the anal also. It differs from 
Pyenosterinx davisii, by the greater length of the neural and hemal spines, 
and the proportionately shorter interspinous processes. The length of the 
anterior articulated ray of the dorsal fin, and rapid diminution in the length 
of the succeeding rays, gives the fin a very triangular form—a feature which 
does not prevail to the same extent in any other species. In allusion to its 
graceful outline, I have appended the nomen triviale gracilis to this species of 
Pycnosterinx. 
Formation and Locality.—Upper Cretaceous: Sahel Alma, Mount Lebanon. 
Ex coll_—Lewis Collection, British Museum, Natural History Department. 
Pycnostering dubius, Davis. 
(Pl xxix,, fig; J.) 
Specimen imperfect; the anterior part of the head and the caudal fin are 
absent; the distal extremities of both the dorsal and anal fins are also wanting. 
The body of the fish is 3:0 inches in length from the anterior part of the 
head preserved to the base of the tail; the head occupies of this 1:3 inch. 
The height at the base of the anterior ray of the dorsal fin is 15 inch; the 
outline of the body is oval, slightly more attenuated towards the snout than 
the tail. The head is not well preserved; the orbit is high, large, and round ; 
the jaws are not preserved; the operculum is large, and its posterior margin is 
circular. 
The spinal column comprises twenty-eight vertebra, of which seventeen are 
caudal; they are as high as long, deeply contracted medially. It is possible 
that one or two additional vertebrae would be present if the caudal extremity 
were complete. The ribs are short and not very strong. The neural spines 
are short and thick; the interspinous bones are numerous, strong, and propor- 
tionately long as the spinous are short ; the heemal spinous and interspinous bones 
are similar to those supporting the dorsal fin; a large anterior spinous bone 
supports a spatulate bone of more or less triangular form, to which are attached 
the anterior spinous rays of the anal fin. 
