6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I39 



the intervertebral area; thus the supposed intercentra here may be 

 parts of the ribs. However, there appears to be a distinct intercentral 

 space coincidental with the position of the ribs, and, in any case, the 

 evidence for intercentra in the anterior caudals is clear and unobscured 

 by ribs. 



Evidence of 24 presacral ribs on the left side is fairly clear, although 

 the first presacral is difficult to see, and only the distal tip of the 24th 

 presacral is preserved on the edge of the slab. The general pattern 

 and number of the presacral ribs and the far anterior position of the 

 left manus have led to the opinion (Romer, 1950, p. 641) that the 

 presacral count is significantly higher than the 25-27 vertebrae usually 

 found in the most primitive reptiles. However, the 5 most anterior 

 ribs are clearly more massive than following ribs, and the distal ends 

 are slightly spatulate — all indicative of an extreme anterior thoracic 

 position related to serrati muscles of the pectoral girdle. Also, the 

 successive positions of the distal ends of the 5 anterior ribs suggest 

 a progressive shortening in a forward direction as might be expected 

 in a smooth transition to the cervical region. Accordingly, a recon- 

 struction will show that the total number of presacrals may have been 

 as few as 28. The forward position of the left manus as an indicator 

 of a far anterior position of the pectoral girdle is probably misleading. 

 The girdle probably shifted forward or to the right side away from its 

 life position lateral to the 5 anterior ribs. 



Rib heads are obscured in the presacral series generally, but the 3d 

 to 8th left presacral ribs appear to have a proximal expansion com- 

 mensurate with the elongate diapophysis of the neural arch. Certainly 

 these ribs are not single-headed as in lizards, but bear a general re- 

 semblance to captorhinid ribs. 



The pelvic girdle and sacral vertebrae are distorted beyond certain 

 recognition of salient features, although the spacing of vertebral seg- 

 ments and disposition of lumbar and caudal ribs suggest the presence 

 of two sacral vertebrae. A short, thick element lying across the ad- 

 ductor fossa of the right femur may be a right second sacral rib ; an 

 obscure spatulate structure immediately anterior to the anteriormost 

 left caudal rib may be the first or principal sacral rib. Except for a 

 general outline of the acetabular regions of the girdle, little can be 

 demonstrated here except that the mass lying between the heads 

 of the femora probably constitutes a pelvic girdle and sacrum of 

 primitive reptilian plan. According to my interpretation, Moodie 

 (1909, pi. 5) included the internal trochanter of the left femur in his 

 outline of the left acetabular region, thus giving the left pelvis a more 



