. Bulletin of the British Museum (Natural History). UPPER JURASSIC PLESIOSAUROIDEA 309 The anterior ramus of the squamosal terminates in a large sutural surface, but there is no indication of the nature and direction of the elements with which it was united. The ventral ramus has the same structure as in C. eitrymenis: on its medial surface is a large facet for the quadrate, above which is a small facet for the paroccipital process of the exoccipital- opisthotic. The quadrate (Fig. 33) is relatively larger and proportionally longer than in the preceding genera. Ventrally it forms two ovoid con
. Bulletin of the British Museum (Natural History). UPPER JURASSIC PLESIOSAUROIDEA 309 The anterior ramus of the squamosal terminates in a large sutural surface, but there is no indication of the nature and direction of the elements with which it was united. The ventral ramus has the same structure as in C. eitrymenis: on its medial surface is a large facet for the quadrate, above which is a small facet for the paroccipital process of the exoccipital- opisthotic. The quadrate (Fig. 33) is relatively larger and proportionally longer than in the preceding genera. Ventrally it forms two ovoid condyles for articulation with the lower jaw, the lateral condyle being slightly larger than the medial. The large lateral facet for the squamosal is 5-7 cm long; above its dorsal end is the conical primary head, which was tipped with cartilage. From this prominence the dorsal edge of the quadrate describes an inward, forward and downward arc which terminates along the upper edge of the pterygoid facet and was continued by the pterygoid. The large pterygoid facet is vertically orientated, extends for 4-8 cm from the dorsal margin to the inner angle of the medial condyle, and faces postero- medially at c. 20° to the long axis of the skull: the anteromedial margin is thin and broken, and may possibly have continued as a thin film of bone further anteriorly across the lateral surface of the pterygoid, its ultimate extent being indicated by a ridge on the pterygoid. The mechanism of suture of the two elements in the present specimen, where the quadrate extensively overlaps the pterygoid anterolaterally, is the reverse of that described in Muraenosaurus and Tricleidiis. where the posterior end of the pterygoid fits into an anterolateral notch in the quadrate. Parts of both pterygoids are preserved, the right being the more complete (Fig. 34). It is an elongated element consisting of a long, thin and horizontally orientated anterior part which was involved in the formation of the palat
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