ICHTHY0SATTRIDJ3. 



73 



the flattening of the nasals, as well as the cordiform cer- 

 vical vertebrae, apparently indicate that this specimen 

 belongs to the present group. The teeth are small. The 

 rostrum is shorter than in /. tenuirostris, and the flat- 

 tening of the nasals and the smaller orbit also distinguish 

 this skull from that species. The contour of the mandible 

 differs from that of /. lonehiodon, and the cupping of the 

 vertebral centra is deeper. The articular bones of the 

 mandible are in situ. In size this specimen agrees nearly 

 with the skull of /. tenuirostris, No. E. 1126. 



Presented by the Rev. T. 8. Montefiore, 1878. 



R. 1168. The posterior portion of a smaller skull specifically indis- 

 tinguishable from the preceding ; from Lyme-Regis. This 

 specimen has been only slightly crushed ; the characteristic 

 flattening of the nasals is well shown. Both sclerotic 

 ossifications are well preserved, and the posterior teeth 

 remain. No history. 



Ichthyosaurus acutirostris, Owen 1 . 



Syn. Ichthyosaurus longipinnis y Mantell 2 (in parte). 

 (?) Ichthyosaurus microdon, Wagner 3 . 

 (?) Ichthyosaurus quadriscissus, Quenstedt 4 (in parte). 



Closely allied to the next species, but distinguished by the curved 

 rostrum and the shorter supratemporal fossae. In the rostrum the 

 alveolar border of the premaxilla is concave, and that of the dentary 

 convex. 



The skeletons of Ichthyosaurs from Wurtemberg containing 

 foetuses figured by Seeley in the 'Hep. Brit. Assoc.' for 1880, pi. i., 

 apparently belong to this species, and probably correspond to 

 I. quadriscissus of Quenstedt (see No. 11. 971). /. microdon, from 

 Wiirtemberg, was subsequently identified by its describer as a variety 

 of /. acutirostris. 



This species is confined to the Upper Lias. 



Hab. Europe (England and Germany). 



14553. Slab showing the right lateral aspect of the skull, a coracoid, 



{Fig.) the pectoral limbs, of which one is entire, and other 



fragments of the anterior part of the skeleton of a large 



1 Kep. Brit. Assoc, for 1839, p. 121 (1840). 



2 Petrifactions and their Teachings, p. 378 (1851). 



:) Abh. k.-bay. Ak. Wies. vol. vi. pt. 2, p. 509 (1851). 



1 Die Jura, p. 210 (1858). The name is merely given in the plural as that of 

 a group, but has been subsequently quoted as a specific one. 



