4 O. C. Marsh on the Remains of a new Enaliosaurian. 



vertebra, in fact, with the exception of a small fracture, seems to 

 be nearly as perfect as in its original condition ; and from it the 

 description and measurements which follow are mainlj taken. 



A close examination of the fossils shows, that, subsequent to 

 the death of the animal, and before being imbedded in the shale, 

 they were subjected to considerable violence. One of them has 

 been pushed aside from its original position about one-third of 

 its diameter, and also turned on its axis about 90°, so as to leave 

 its superior surface in apposition with the lateral surface of its 

 fellow. Through the center of the anterior vertebra an irregu- 

 lar cavity has been made, and a wide fissure separates a segment 

 from the rest of the centrum (Plate I. figure 2). The edges of 

 each of the fossils are somewhat abraded, apparently from hav- 

 ing been rolled about by water: this, however, could not have 

 been long continued; as the delicate reticulated texture of the 

 non-articular surfaces, being protected by their slight concavity, 

 IS perfectly preserved (Plate I. figure 1, and Plate II. figure 4). 

 These injuries were evidently all received before the entomb- 

 ment of the vertebra ; and, as no similar remains could be found 

 in the vicinity when these were discovered, it is quite probable 

 that the same force, which caused the injuries, also widely sepa- 

 rated the different parts of the skeleton. 

 ^ The general form of the vertebra? is cylindrical, but their 

 Bides are somewhat compressed obliquely, which gives to the 

 contour of the centra a subhex agonal appearance. They are 

 much flattened m the direction of the antero-posterior diameter, 

 which has to the transverse diameter about the proportion of 1 

 to 3. Both the articular terminal facets are deeply and equally 

 concave; but from the center to the margin the surfaces are 

 convex, and this convexity is greatest near the center, as repre- 

 sented in Plate II. figure 2. The cavities for the reception of 

 the intervertebral matter begin immediately from the margin; 

 and are considerably deeper than in the corresponding parts of 

 the IchiJiyosaurus, indicating a greater degree of flexibility in 

 the spinal column. The margins of the vertebra are somewhat 

 raised, as if they had yielded to a forcible compression applied 

 longitudinally ; and hence the lateral surfaces of the centers are 

 concave in an antero-posterior direction. This concavity is 

 greater m the upper half of the vertebra, and was undoubtedly 

 more marked originally than at present, since the appearance o"f 

 the margins indicates considerable abrasion. The non-articular 

 surtaees of the centra are smooth and regular; and the external 

 n Ores ot the osseous tissue f ' ' ' ..... 



Plate L figure 1, and in the 



,J^\f neurapophyses are not anchylosed .. .... ...,,, 



the Mammalia, nor connected to it by sutures, as in tl 

 diles ; but their union with the vertebra is indicated by 



