_Plioplatecarpus_ Dollo is described by its author as having a sacrum of two conjoined vertebrae,[10] by reason of which it is placed in a separate family from the rest of the _Pythonomorpha_. It may be presumptuous to express a doubt of the genuineness of the sacrum, and yet, save from the fact that the author found two specimens quite alike, one might doubt it strongly. It is not very rare that two, or even three vertebrae are found united from injury in these animals, and such would readily account for the consolidation as figured and described by Dollo, except for the coincidence of the second specimen. A stronger reason for doubt is the statement that the consolidated vertebrae belong to the posterior “lumbar” region, and that the last vertebrae had small tubercles indicative of chevrons. In the reptiles which we have examined, the chevrons do not begin immediately behind the pelvis, but are separated by a longer or shorter region in which the vertebrae bear elongated diapophyses alone. If the conjoined vertebrae figured by Dollo are in reality sacral, it would appear that the animal is an exception to _Clidastes_ and such lizards as we have examined. Furthermore, the pelvis must have been of a different structure from that in the Kansas genera of the Pythonomorpha, for, in these, it is evident that the ilium had an oblique position, and could have been attached to but a single diapophysis. [10] Bull. Su. Mus. Roy. S. Hist. Nat. d. Belg. i, p. 8, 1882. CLIDASTES WESTII, N. SP.