192 MAEINE EEPTILES OF THE OXFORD CLAY. 



Least width between the orbits i'5 



Width at outer angles of prefrontals 13 - 



Length of the frontal anterior to the temporal fossae .... 7-9 



In the C.ital. Foss. Rept., Brit. Mus. (pt. iv. p. 232) Mr. Lydekker refers this 

 specimen to M. superciliosum, but, for the reasons given above, it seems more probably 

 to belong to M. moreli. 



E. 2040 (Leeds Ooll. 15). Imperfect skull, probably of this species. 



Metriorliynclms Iseve, n. sp. 



[PI. X. ; text-figs. 65, 69 B, 73 A.] 



Type Specimen. — Skull (PI. X. figs. 1, 2 ; text-fig. 73, A), mandible, atlas, axis and five 

 other cervicals, sixteen dorsals, all much crushed, cervical and dorsal ribs, coracoid, 

 scapula, humerus, and right femur (R. 3015, Leeds Coll. 0). This specimen is selected 

 as the type rather than the more nearly complete skeleton no. R. 3014, because the 

 skull is in a better state of preservation. 



The skull (PL X. fig. 1 ; text-fig. 73, A) is long and slender, and there is scarcely a 

 trace of sculpture on any of the bones. The bar between the temporal fossa? is broad, 

 especially in the frontal region. The anterior end of the frontal extends nearly to the 

 level of the anterior angles of the prefrontals. The nasals are separated from the pre- 

 maxillse by an interval equal to about half their own length. The teeth are numerous, 

 small, and rather close-set (PI. X. fig. 2), there being ten teeth in the anterior ten 

 centimetres of the mandible ; their crowns are somewhat compressed, and the enamel 

 only slightly sculptured with irregular ridges. The exact number cannot be made 

 out, but there seem to have been upwards of 30 on each side of a mandible, the total 

 length of which is about 49 cm. 



The fore limb (text-fig. 69, B) is greatly reduced, the humerus being shorter than the 

 scapula, which exceeds the coracoid in length; the reverse is the case in II. super- 

 ciliosum. On the other hand, the tibia (PI. X. fig. 3) is a little longer in proportion to 

 the femur than in M. superciliosum. The slenderness of the skull, the absence of 

 sculpture on the frontals and other bones, the comparative smoothness of the teeth, 

 and the great reduction of the fore limb, point to the probable descent of Geosaurus 

 gracilis from this or a closely similar species. 



E. 3015 (Leeds Coll. 0). Skull (PI. X. fig. 1), mandible, atlas, axis, and five other cervicals, sixteen 

 dorsals, all much crushed, cervical and dorsal ribs, coracoid, scapula, humerus, right 

 femur. Type specimen. 



