than that of the Camarasaurus supremus, but is not so robust. The shaft 

 is nearly round and somewhat contracted at the middle, where it is slightly 

 convex backwards. It is slightly curved inwards at the great trochanter. 

 Here the shaft is moderately grooved on the posterior face. This trochan- 

 ter is only a prominent ledge below the head. The third trochanter is sit- 

 uated a little above the middle of the shaft ; it is a prominent obtuse ridge 

 directed backwards. The condyles are extended well posteriorly, and are 

 separated by a deep groove, which originates on the inferior portion of the 

 shaft. They are also separated anteriorly by a shallow open groove. The 

 external condyle is rather more robust than the internal. 



The length of the femur is six feet four inches ; the elevation of the 

 dorsal vertebra three feet three inches. 



Measurements. M. 



i fore and aft 245 



Diameter of dorsal centrum vertical 270 



(transverse 265 



Total elevation of vertebra 1 . 100 



Length of neural spine 600 



Elevation of anterior zygapophyses 500 



f antero-posterior 160 



Diameter of neural spine - transverse (at middle) 065 



(_ " at summit 140 



Depth of centrum below pneumatic foramen 120 



Fore and aft diameter of pneumatic foramen 080 



Length of pubic bone 1.060 



Thickness of stoutest extremity 140 



Length of femur 1.524 



Transverse extent of proximal end .420 



" "condyles 320 



Diameter of middle of shaft 220 



Distance from head to third trochanter 665 



Diameter of head (compressed) 260 



Amphicceltas latus sp. nov. 



Of the wonderful fauna of the Dakota epoch of the Rocky Mountains 

 the Camarasaurus supremus was preeminent in several proportions, the 

 AmpMcceUas altus was the tallest, and the saurian now to be described, was 

 the most robust. It is represented in Mr. Lucas' collection by a right 

 femur and four caudal vertebrae which are in good preservation. They reveal 

 the existence of another saurian of huge dimensions, and of great mass in 

 proportion to its height. 



The caudal vertebrae are apparently from the anterior part of the series. 

 They are ail strongly bi-concave ; the anterior face more so than the pos- 

 terior. They all possess diapophyses of depressed form which take their 

 origin below the base of the neural arch. The centra are short in antero- 



