10 PKOCEEmisrGS of the national, museum yol. 69 



(3) Vertebrae of Metoposauridae from the Middle Trias of Tan- 

 ners Crossing, Ariz. (Cat. No. 2158, U.S.N.M.). The dorsal verte- 

 brae are broad and with flat and parallel articular faces. The dorsal 

 side shows an inclined anterior and a similar posterior face, and 

 between them a slightly curved or nearly flat transverse strip with 

 no trace of the dorsal sine canal. The attachment of the rib is 

 shown by a thickening of the anterior and the posterior lateral 

 border in their middle height. 



A middle caudal vertebra, smaller than the dorsals, is rather nar- 

 row. Its articular faces are very slightly converging upward. The 

 upper aspect shows two faces, one inclined anteriorly, the other 

 posteriorly. It is demonstrated more clearly than in the dorsals that 

 this "centrum" is really a hypocentrum. From below it has a very 

 deep median fossa and two high ridges, slowly becoming higher pos- 

 teriorly, and being broken below the posterior articular face. This 

 is the place where the bifurcated haemapophysis grew out of the 

 hypocentrum ; it was not separated from it as in reptiles, but was one 

 single piece. At the posterior border of the hypocentrum and low 

 down there is a small remainder of the attachment of the caudal rib. 



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