in North America of rare Extinct Vertebrates. 207 



one of those received, is characterized by its undivided trans- 

 verse neural spine. The entire neural arch is of enormous 

 elevation; but as the zygapophyses " (PI. X. fig. 4, Zj s'; 

 the letters indicative of parts are added to my copy, not being 

 given in the original) " are above its middle, the neural spine 

 [ib. ns] is not as long relatively as in various other genera, or 

 as in the caudals of this one. The sides of the centrum [c] 

 are strongly concave, and the borders of the cup [c'] flaring. 

 The neural arch is everywhere excavated, so as to reduce the 

 bulk and produce lightness so far as consistent with strength. 

 The diapophyses {d\ rise from a point above the neural canal, 

 and are directed upwards as well as outwards. It sends a 

 narrow ridge down to the sides of the centrum, on each side 

 of which its shaft and base are deeply excavated. The 

 posterior of these fossge is overlooked by the wide zyga- 

 pophysis \z''\ ; and the roof of the anterior one supports 

 the anterior zygapophysis [_z\. The former are separated by 

 another and vertical septum, which bifurcates below, forming 

 two prominent borders [», w'] of the neural canal. At each 

 side of the base of the neural canal there are two trilateral 

 fossffi, of which the anterior [^?] is much larger and extends 

 higher up on the lateral edge of the spine. They are sepa- 

 rated by a lamina. The diapophysis [c?] is not very long, 

 and is subtriangular in section near the extremity. The 

 neural spine is thickened at the extremity as though for the 

 attachment of a huge ligament. At the summit of its poste- 

 rior basal fossa, at the middle of its height, is an outwardly 

 curved process, with a smooth extero-superior face. 



" Measurements. 



m. 



" Length, of centrum '275 



Total elevation of vertebra -830* 



Elevation to posterior zygapophyses "ooO 



Elevation of superior edge of diapophyses above cen- 

 trum "350 



Elevation of neural spine above posterior zygapo- 

 physes '295 



Length of diapophysis behind '215 



Depth of extremity of ditto (restored) '075 



Transverse extent of summit of neural spine "215 



„ „ neural spine at middle '330 



" Another dorsal vertebra is better preserved than the last 

 described. It is distinguished by the lack of the median 

 portion of the neural spine and the extension outwards of the 



* [=2 feet Scinches.] 



