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Show 1891.] HELODERMA HORRIDUM AND H. SUSPECTUM. 115 may be likewise objected to on the ground that it is not expressive of the position assumed by the element in a great number of Reptiles. Fig. 5. j> Three posterior dorsal and three anterior caudal vertebra; of Heloderma suspectum, 8 (a) and $ (b), and H. horridum, § (c); nat. size. I therefore think it best to retain the name hypapophysis (Owen), of which intercentrum (Cope) becomes a synonym. Turning back again, after this somewhat lengthy digression, to the tioned that the zygosphenal articulation of the vertebras exists in Tupinambis and Tencs as in most Iguanidce. Owen was mistaken in denying the existence of the zygosphene in Amblyrhynchus, where it is present as in most Iguanoids, including Phrynosoma and Basiliscus ; only two Iguanoid genera are known to me to lack this additional articulation, viz., Anolis and Polychrus. It appears to m e very probable that the Lizards from the Eocene of W y o m ing, described by Marsh (Am. Journ. (3) iv. 1872, p. 299) under the name of Thinosaurus, as having vertebras resembling those of Varanus, but with zygosphenal articulation, belong to the family Teiidce, and there can be no shadow of a doubt that the Cretaceous (Neocomian) Hydrosaurus lesinensis of Korn-huber (Abh. geol. Eeichsanst. v. 1873, H . 4, pi. xx.), placed by Zittel in the Varanidce, belongs to the Dolichosauridce, possibly to the genus Dohchosaurus proper. |