FROM THE CAMBRIDGE GEEENSAJTD. 



219 



is 13 millim., but rather more dorsally, and slightly less on the 

 centrum as the sutures with the transverse processes diverge upward. 

 The prezygapophyses are broken away, but the width across them 

 from side to side was about 9 millim. Behind the transverse pro- 

 cesses the bone is notched in, so that the neural platform projects 

 backward to form the postzygapophyses, and the measurement is a 

 little less over them from side to side than over the prezygapophyses. 

 The dorsal aspect of the neural arch is the most distinctive feature 

 of the specimen, each half of it being horizontal and flattened, with 

 a depression at the base of the neural spine, which was narrow and 

 is broken away. There is no trace of zygapophysial ridges such as 

 occur in Varanus and some other lizards. The neural canal is ver- 

 tically ovate in front, and reaches nearly the height of the neural 

 arch, 7 millim., while the transverse measurement is over 5 millim. 



The transverse processes are directed outward and backward as 

 in the first vertebra of existing lizards (fig. 12). They are compressed 

 from side to side and from above downward, so that the transverse 

 section is vertically oblong and inclined a little backward. The 

 process extends from the base of the centrum to the platform of the 

 neural arch, and is 11 millim. deep at the suture. It is 8 millim. 

 wide at the base and 5 millim. wide at the neural platform, so that 

 the flattened anterior aspects look obliquely forward, outward, and 

 upward. The posterior aspect is vertical, with a transverse concavity 

 in the middle. The posterior margins of the processes appear to 

 have been sharp and angular, while the anterior margins are slightly 

 rounded. Both upper and under surfaces are flattened and converge 

 outward. The width of the fragment, as preserved, is 24 millim. 



The most distinctive^e^rtul : eT~of~ihis vertebra are found in the 

 convexity of the base of the centrum, and in the transverse pro- 

 cesses rising to the level of the flattened neural platform. 



I am acquainted with no form of sacrum which approximates 

 toward this fossil so as to need to be distinguished by further 

 comparison. 



EXPLANATION OF FIGURES. 



Plate XII. 

 (The figures are of the natural size.) 



Fig. 9. Antero-superior aspect of femur of Patricosaurus merocratus. 



10. Proximal aspect of the same bone. 



11. Anterior aspect of first sacral vertebra. 



12. Inferior aspect cf first sacral vertebra. 



Discussion". 



Mr. Htjlke said Ornithodesmus was another old acquaintance of 

 his. Several bones were found with it, now lost. He had looked 

 upon it as Pterodactylian. 



Mr. Blaneord suggested that the name Patricosaurus should be 

 founded on one specimen, not on the two, lest they should prove to 

 belong to distinct animals, and confusion result as to which should 

 bear the name. 



Q2 



