SUPPLEMENT. 273 



but has more prominent costal articulations — a difference 

 which may not improbably be explained partly by indi- 

 vidual variation, and partly by the edges of the costal 

 articulations of the latter having been broken. On the 

 right side the two costal facets are separate, but on the 

 left they have coalesced. This and the preceding speci- 

 men closely resemble the vertebrae from the Oxford Clay 

 of Huntingdonshire, to which the name P. pachydirus 

 (vide supra, ii. p. 145) was applied. 



Genus PELONEUSTES (supra, ii. p. 151). 



It appears that all the smaller forms hitherto included in Plio- 

 saurus should be referred to this genus, in which the cervical centra 

 are generally longer in proportion than in the latter, their length 

 being usually greater than half the vertical diameter of the terminal 

 faces. The vertebrae referred to P. cequalis {supra, ii. p. 153) are, 

 however, relatively shorter than in the Oxfordian species, unless this 

 is due to the effects of pressure. It appears that the pelvic limb 

 is larger than the pectoral, and that the humerus and femur have 

 a nearly similar distal contour. In fig. 50, Pt. II. p. 154, the post- 

 axial expansion of the distal extremity is broken away, the same 

 being the case with the propodial of No. 474 L0 (ibid. p. 158). Both 

 the latter specimen and the one represented in Pt. II. fig. 52, p. 155, 

 are pelvic limbs. 



Peloneustes evansi (Seeley). 



Syn. Pliosaurus evansi (supra, ii. p. 128). 



A comparison of the undermentioned specimens with the cervical 

 vertebrae of P. philarchus shows that they can only be distinguished 

 by their larger dimensions. It is probable that the mandible and 

 paddle in the Eyebury Collection, noticed in Pt. II. p. 154, belong 

 to this form, since they agree in relative size with the vertebrae x 



The originals of the following specimens belong to the type series ob- 

 tained from the Oxford Clay near St. Neots, Huntingdonshire, 

 and preserved in the Woodwardian Museum, Cambridge (vide 

 supra, ii. p. 129). The casts were made in the Museum in 



1889. 



R. 1713. Cast of the centrum of the fourth cervical vertebra. 

 Original figured by Seeley in the ' Quart. Journ. Geol. 



1 See Quart. Journ. Geol. Soc. vol. xlvi. p. 52. 



TAET IV. T 



