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PROCEEDINGS OF THE NATIONAL MUSEUM 



as the bones Avere of corresponding size and there was no apparent 

 duplication of parts it is assumed that all pertain to the skeleton of 

 a single individual. 



A small fragment of the left maxillary (fig. 1, A) is the only rec- 

 ognizable skull part of this specimen preserved. It shows the ex- 

 ternal surface of the bone to have been sculptured. Alveoli for three 

 teeth indicate the thecodont nature of their attachment and the ovate 

 shape of their roots, with the longer diameter longitudinal. 



In all there are seven complete vertebral centra and fragmentary 

 parts of several others. Dorsal, sacral, and caudal vertebrae can cer- 

 tainly be recognized, and there is one centrum that is provisionally 

 identified as pertaining to the axis. It differs from all others in 



Figure 1. — Skeletal parts of Pinacosuckus mantiensis, type (U. S. N. M. No. 16592) : A, 

 Maxillary fragment; B, proximal end of left coracoid. Both figures three times nat- 

 £ ural size. 



having a flattened anterior articular end, on each side of which are 

 small facets that look forward and outward. This centrum is de- 

 pressed and is wider in front than behind, with a broadly rounded 

 ventral surface as shown in figure 2. The posterior articular end 

 is cupped. The centrum has a greatest length of 9 mm. and a great- 

 est width of 7.5 mm. 



Two dorsal centra differ in that one is compressed and the other 

 depressed. It is thought that the former pertains to the anterior 

 dorsal region, the latter to the posterior part of the presacral series. 

 Both have small portions of the neural arch present, but the absence 

 of any trace of the sutural connections with the centra suggests the 

 adult age of the individual. Both have evenly rounded ventral 

 surfaces without trace of a keel. The anterior dorsal centrum meas- 

 ures 8 mm. in length, the posterior one 7 mm. 



The two sacral centra (fig. 3) were found detached from each 

 other, but their roughened sutural ends made perfect articulation. 

 These centra have a combined length of 14.3 mm. The centra are 

 depressed, with cupped, ovate, articular ends and broadly rounded 

 ventral surfaces. Sacral ribs attach with the center of the centra. 



