The vertebral series in this specimen is composed of seven cervicals, twenty-three dorsals, seven pygials, and eighty chevron-caudals. The relative proportions of the different regions in the two genera, as shown by the two specimens of _Clidastes_ and _Liodon_, may be represented as follows. The first column is for _Clidastes_. Skull 12.1 11.1 Neck 6.5 6.8 Trunk 39.2 28.0 Tail 42.3 54.1 Limbs. The figures in plates II and III will give a sufficiently good idea of the limbs in this specimen. They are figured as they were lying, showing the outer sides of the coracoid, scapula and pelvic bones, and the palmar or plantar surface of the remaining bones. Coracoid. It will be observed in plates II and IV that there are two very different types of coracoid, one with a deep emargination, the other without the slightest indication of such. The same non-emarginate form occurs in _C. tortor_, as specimens in our Museum show, in _C. propython_ Cope (Ext. Batr. etc. pl. xii, f. 16,) and in _C. dispar_, as figured by Marsh[7], and as stated by him in the same paper (“There is certainly no emargination in the coracoid of _Clidastes_, _Edestosaurus_ and _Baptosaurus_, as specimens in the Yale Museum conclusively prove.”) It is true that Marsh in a later paper[8] figured a specimen with emarginate coracoid under the name of _Edestosaurus dispar_, but it is certain that his identification of his own species was wrong, as will be seen by comparing his figures. From the senior author’s memory of the specimen with the emarginate coracoid figured, and from the figure itself he feels confident that the second specimen is _C. velox_. [7] Amer. Journ. Sci. iii, pl. xi, f. 1, June, 1872. [8] Amer. Journ. Sci. xix, pl. i, fig. 1, Jan., 1880. That the emargination was overlooked by the author seems strange, as in the same paper in which this figure is given occurs the description of _Holosaurus, founded upon that very character_. If the emargination is sufficiently important to base a genus in the one case, then it should be in the other, and the character could not be applied to _Edestosaurus_, based upon characters which it hardly seems possible that the author himself could seriously consider, for _E. dispar_ was the type of _Edestosaurus_. It will be observed, further, that the figured coracoids differ very materially in size, those with the emargination pertaining to a small species, while _C. dispar_ is one of the largest. In our Museum there are three specimens with the emarginate coracoid, all of them small or very small, the described specimen of _C. velox_ being the largest.