498 



Annals of the Carnegie Museum. 



Fig. io. Dorsal of Elosau- 

 rti.s parvus, seen from left side 

 (No. 566), ^ natural size, sdc, 

 supradiapophysial cavity; pdc, 

 postdiapophysial cavity ; adc. , 

 prediapophysial cavity; idc, in- 

 fradiapophysial cavity. 



The horizontal lamin;^ extend almost horizontally from the pre- 

 to the postzygapophyses meeting in the 

 transverse processes. The inferior blades 

 of the prezygapophysial laminte are re- 

 markably heavy, but the superior portion 

 is wanting. The neural arch is compara- 

 tively large and nearly round. In gen- 

 eral the arch has a low massive appear- 

 ance like the transverse extension ob- 

 served in Morosaurus. The arch was 

 united to the centrum by a very coarse 

 sutural articulation. Of the cavities all 

 four of the diapophysial cavities are pre- 

 sent, the pre- and post- being the most 

 pronounced. The infrazygapophysial cav- 

 ity is comparatively shallow. See Fig. 10. 

 Measurements. 



Greatest length from anterior to posterior zygapophyses, 57 mm. 2j?g in. 



Greatest expanse from end to end of transverse, 99 mm. 3^ in. 



SacniDi. — The two sacral centra, which have been provisionally 

 referred to this specimen are short, broad and comparatively solid, 

 much resembling the sacral vertebrae of Plciirocivlus nanus }^ Both 

 ends of the centra are flat and there is no evidence of their having 

 been coossified, though the absence of this character may be due to 

 the young age of the individual. The attachments for the sacral ribs 

 are very broad, extending over nearly the entire sides of the centra. 

 Superior to the rib attachments are two pits extending down obliquely 

 toward the center of the centrum. These pits are more pronounced 

 on No. I " than on No. 2. Inferiorly the neural canal at this point 

 is enlarged by peculiar wedge-shaped pits which extend deep down into 

 the centra. It is observed in both instances that the lateral dimen- 

 sions are much greater than the longitudinal. 



Measurements. 



No. I. 



72 mm. 2j-^ in. 



88 mm. t,]^ in. 



61 mm. 2;^s in- 



'° Marsh, see American Journal of Science, Vol. XXXV. 



" These numbers are used to designate the vertebrae and have no reference to their 

 position in the sacrum. 



No. 2. 



Greatest length of centra, 

 Greatest width of centra, 

 Greatest depth of centra, 



