108 THE WASATCH AND BUIDGER FAUN^. 



One of the dorsal centra is split vertically and longitudinally, and shows 

 the structure already figured by Leidy in the Ischyrosaurus antiquus* Leidy. 

 The surface exposed displays two diagonal lines of fissure crossing each 

 other at right angles. They indicate clearly the mode of origin of this 

 amphiplatyan type of centrum. The centrum is first deeply amphicoelous, 

 as in the Theromorphous reptiles of the Permian. The conical cavities are 

 filled by the ossification of the remaining portion of the notochord, forming 

 a conical body which always remains • distinct from the remainder of the 

 centrum. 



The articular faces of the dorsal centra are a little wider than deep, 

 and the depth about equals the length of the body. They are not nearly 

 so depressed as those of C. australis, and their outline is diff"erent. This is 

 wider above and narrows below; in both C. australis and C. sajionensis the 

 inferior outline is part of a circle. None of the dorsals preserved are keeled 

 below. There is a fossa below the diapophysis which has a subvertical pos- 

 terior boundary. The general surface (somewhat worn) does not display 

 wrinkles near the articular faces. An anterior dorsal has a short compressed 

 diapophysis with a narrow figure 8 articular surface, and its superior border 

 in line with the roof of the neural canal. The anterior caudals have sub- 

 round articular faces; the posterior are more oval, and the bodies com- 

 pressed. With greater compression the length increases. 



Measurements. 



u. 



I anteroposterior 0-i5 



Diameters of an anterior dorsal s vertical (hJ5 



( transverse 030 



Heiffht of costal facet of do .'. 021 



_. . , lit vertical 007 



Diameters neural canal do. ( 



I transverse 009 



/ anieropoeterior 0"24 



Uianieters anterior caudal < vertical 021 



( transverse 021 



Santeropoaterior 025 

 vortical 018 

 transverse 018 



The typical specimen was found by Mr. Baldwin near the Puerco River 

 west of the Nacimiento Mountain, New Mexico, in the typical locality of 

 the Puerco formation. 



•Trans. Auicr. Philog. Soo. 1860. 



