GILMORE: OSTEOLOGY OF BAPTANODON (MARSH) 125 
OPHTHALMOSAURUS ICENICUS, Seeley. 
Ophthalmosaurus icenicus, Seeley, H. G., Quart. Jour. of the Geol. Soc. of London. 
Vol. XXX., 1874, pp. 696-707. 
This, the type species of the genus, was based upon quite a complete pectoral 
girdle and portion of a fore limb, the latter pertaining to a second individual. The 
type was found in the Oxford clay by Mr. C. Leeds, who later submitted it to Pro- 
fessor Seeley for description. The remains of four or five individuals preserved in 
the collections of the British Museum, and referred to this species by Lydekker 
have all been found in the Kimmeridge clays which is considered Upper Jurassic, 
while the type is from Middle Jurassic. 
The following specific characters constitute the essential differences as character- 
ized by Lydekker in the Catalogue of Fossil Reptilia and Amphibia in the British 
Museum. 
Sp. char.: “Larger than the type of the following species. The post-axial facet 
smaller than that of the radius; and the antero-posterior diameter of the proximal ex- 
tremity of the humerus less than that of the distal extremity. In the cervical region the 
cupping of the anterior face of the centrum confined to the central portion and surrounded 
by a flattened periphery. 
OPHTHALMOSAURUS CANTABRIGIENSIS, Lydekker. 
Ophthalmosaurus cantabrigiensis, Lydekker, R., Geol. Mag., Decade III., Vol. V., 
July, 1888, No. 7, p. 309. 
This species was first proposed by Lydekker in a note to the Geological Maga- 
zine, the description appearing later in the Catalogue of the Fossil Reptilia and 
Amphibia in the British Museum. The material upon which this species is based 
consists of a right humerus from the Cambridge Greensand. 
The equal size of the three distal facets of the humerus, and their greatest elonga- 
tion being vertical to the plane of articulation at once distinguishes this species from 
Baptanodon. Lydekker in his original description adds, ‘This species may belong 
to Baptanodon.” In reality the type of the genus (O. icenicus) is more closely 
allied to that genus. 
The type, No. 43989, is preserved in the British Museum. 
Sp. char.: “ Typically of small size. The three distal facets of the hwmerus nearly 
equal in size, and the antero-posterior diameter of the proximal extremity of the same bone 
exceeding that of the distal.” 
