. Bulletin of the British Museum (Natural History), Geology. l62 A REVIEW OF UPPER JURASSIC PLIOSAURS anterior and posterior margins of the ventral surface of the centrum are somewhat roughened ; there is no evidence of a ventral keel. Description of associated skeleton from Stretham. Teeth. The teeth are similar to those of Pliosaurus brachydeirus Owen, being trihedral in cross-section ; the enamel of the flat outer surface is smooth but the remainder of the crown is characterized by longitudinal ridges. Cervical vertebrae. The ventral surface of the four known anterior cervical verte- brae i
. Bulletin of the British Museum (Natural History), Geology. l62 A REVIEW OF UPPER JURASSIC PLIOSAURS anterior and posterior margins of the ventral surface of the centrum are somewhat roughened ; there is no evidence of a ventral keel. Description of associated skeleton from Stretham. Teeth. The teeth are similar to those of Pliosaurus brachydeirus Owen, being trihedral in cross-section ; the enamel of the flat outer surface is smooth but the remainder of the crown is characterized by longitudinal ridges. Cervical vertebrae. The ventral surface of the four known anterior cervical verte- brae is flat with no suggestion of a ventral keel; the lateral surface of the centra between the superior rib facet and the neural arch is smooth with no indication of a ridge. In the centre of each articular surface a small mamilla is found punctured by a nutritive foramen. Three centra are known from the posterior part of the Fig. 8. Stretosaurus macromerus (Phillips). , Sedgwick Mus. Epipodials and tarsus of left hind limb, in dorsal view, x-|. tib., tibia ; fib., fibula ; tbe., tibiale ; int., intermedium ; fbe., fibulare. All have a large rounded boss in the centre of their articular surfaces, and compared with the anterior cervicals the first two specimens show a marked reduction of the inferior rib facets. In the last posterior cervical centrum only a single rib facet remains, this being borne on a pedicle situated on the upper half of the lateral sur- face of the centrum. A sharp ridge is developed between the dorsal edge of this pedicle and the base of the neural arch, the suture line of which extends laterally towards the rib facet. Scapula. The scapula is a triradiate bone in which the whole surface is in one plane, no part being set off at an angle. The glenoid ramus is thickened and elongated, the ventral plate is not greatly expanded, and the dorsal process is produced anteriorly and does not project laterally. By the anterior production of the dorsal. Ple
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