32 FOSSIL REPTILES OP DORSET. 



afford a perfect knowledge of the animal's structure have been found 

 in the Lower Lias of Lyme Kegis and nowhere else. The head is 

 disproportionately large as compared with the rest of the body, 

 and at the same time exhibits a remarkable economy of material 

 to aid the animal in its aerial flight. The upper-jaw is armed with 

 long, slender, sharp-pointed laniaries, and no small ones as in 

 the lower-jaw ; eleven on each side, at wide intervals from each 

 other. The lower-jaw has only four or five laniaries in the 

 forepart of each ramus, implanted in distinct sockets, with a series 

 of small close-set teeth resembling those of fish. The cranial 

 portion of the skull is extremely small; the rest consists of 

 large and powerful jaws, resembling no other Pterosaurian 

 skull. The neck is short and inflexible, composed of seven 

 vertebrae, of a thickness and strength proportionate to the 

 size of the head and sufficient to overcome and bear away its prey. 

 It appears to have had five or six sacral and about thirty caudal 

 vertebrae. The length of tail was twenty-one inches, which was stiff 

 and capable of sustaining the membrane. The fingers had three 

 intermediate phalanges each, and bore claws ; the wing-finger 

 was the longest and formed the upper support of the wing. 

 The metatarsals of four of the toes of the hind-foot were long and 

 slender ; the fifth probably supported the wing when expanded, 

 hence the necessity of greater strength and thickness of bone. 



GENUS PTEKODACTYLUS, Cuvier. 



This Genus, excepting the largeness of the head and length of 

 neck, strongly resembles the Bat in the general proportions of the 

 body and the modification of the fore-limb, but a closer inspection 

 shews its affinities to be rather reptilian. The wing-finger had four 

 phalanges. The jaw had teeth to the extremity, which were long 

 and slender. The tail was short and moveable. Judging from the 

 form of the skull, the brain-case was small and rounded, similar to 

 that of a bird. It joined the neck beneath, and the nasal opening 

 was just in front of the orbit ; both of these are Avian character- 

 istics. In some species the extremities of the upper and lower jaws 



