ENALIOSAURS. 275 



pointed, laterally compressed, but not trenchant, varying in size ; 

 their number is nine on each side of the upper jaw and seven on each 

 side of the lower jaw ; none of them are implanted in the intermax- 

 illary bone. 



The teeth figured in PI. 63 a, fig. 7, are referred by Dr. Buck- 

 land to the large species of Pterodactyle {Pter. macronyx) , discovered 

 by him in the lias at Lyme Regis ; they are implanted like the teeth 

 of other species of the genus in separate sockets, but in the breadth 

 and shortness, lateral compression, and trenchant anterior and pos- 

 terior margins of the protruded crown, they much more closely 

 resemble the teeth of certain Scomberoid fishes, which are similarly 

 implanted in the jaws. M. H. Von Meyer observes that the jaw of a 

 Pterodactyle from the lias at Banz, which he refers to the species 

 macronyx, contains the sockets of only fourteen teeth, whilst the 

 fragment of jaw with the Sphyrenoid teeth from Lyme Regis above 

 mentioned, must have contained a much greater number. 



Some portions of the skeleton of a large Pterodactyle have been 

 discovered by Dr. Buckland in the oolite at Stonesfield. A few teeth 

 from the same formation, in the collection of the Earl of Enniskillen, 

 bear the same proportion to these bones, as do the teeth of the Pter. 

 crassirostris to its skeleton ; they are long, slender, conical, slightly 

 curved, and sharp-pointed; their base is smooth, the enamelled 

 crown is marked with fine strise, converging obliquely upwards to a 

 longitudinal line on the convex side of the tooth. These teeth vary 

 from nine to fourteen lines in length, and are one line or one line and 

 a half across the base. 



I have not had the opportunity of examining the microscopical 

 structure of an undoubted tooth of a Pterodactyle. 



ENALIOSAURS. 



\20. Ichthyosaurus. — The teeth of the Ichthyosauri have a simple, 

 more or less acutely conical form, with a long and, usually, expanded 

 or ventricose base, or implanted fang. They are confined to the inter- 

 maxillary, maxillary and premandibular bones, in which they are 

 arranged in a pretty close and uninterrupted series, and are of nearly 

 equal size. They consist of a body of unvascular dentine, invest- 



T 2 



