122 



REVISION OF THE PELYCOSAURIA. 



just below the anterior edge of the acetabulum. The ischium is complete ; the upper 

 edge is slightly concave just posterior to the acetabulum, then rises to a slight rugose 

 prominence and falls suddenly to the distal end. The ischia of the two sides meet in 

 a deep symphysis, but this does not extend the full length of the bones, as the distal 

 ends are separated by a slight notch. The suture between the ischium and pubis is 

 not traceable. Viewed from either end the pelvis is seen to have been very narrow 

 and high, fig. 49. 



The /emit r oi Dimetrodott gigas differs from that oi Dimetrodon incisivns in the 

 heavier outer condyle and the slightly curved shaft. In both the femora of this speci- 

 men the lower end has been crushed, so that the face on the outer condyle seems to 

 have been lost, and the groove between the condyles looks outward instead of forward. 

 Another specimen, No. 4024 Am. Mus., of the uncrushed distal end of the femur shows 

 that the groove between the condyles was not so definite as in Dimetrodon incisivus. 



Measurements. — No. 1002 University of Chicago. 



mm. 



Total length of skull 455 



Third cervical : 



Elevation of spine above center of neural 



canal 172 



Length base of centrum including inter- 

 centrum 43 



Anterior face : 



Vertical diameter 34 



Horizontal diameter 36 



Posterior face : 



Vertical diameter 46 



Horizontal diameter 46 



Fourth cervical : 



Length of bottom line 3° 



Posterior face : 



Vertical diameter 49 



Horizontal diameter 46 



First dorsal : 



Length, bottom line of centrum 31.5 



Anterior face : 



Vertical diameter 35 



Horizontal diameter 37 



Second dorsal ; 



Length, bottom line of centrum 29.5 



Posterior face : 



Horizontal diameter 41 



Vertical diameter 49 



Third dorsal : 



Length, bottom line of centrum 25 



Anterior face : 



Vertical diameter 52.5 



Horizontal diameter 37 



Thickness of centrum : 



Opposite notochordal canal 17 



Just below notochordal canal 2.5 



Fourth dorsal : 



Length, bottom line of centrum 26.5 



Anterior face : 



Horizontal diameter 35 



Vertical diameter 45 



Fifth dorsal : 



Length, bottom line of centrum 26 



Sixth dorsal : 



Length, bottom line of centrum 32 



Anterior face : 



Vertical diameter 42.5 



Horizontal diameter 32 



Seventh dorsal : 



Length, bottom line of centrum 32 



Posterior face : 



Horizontal diameter 35 



Vertical diameter 44 



Eighth dorsal: 

 Imperfect. 

 Ninth dorsal : mm. 



Antero-posterior distance on bottom line 



of centrum 34.5 



Posterior face : 



Vertical diameter, crushed 36 



Horizontal diameter 38 



Anterior face : 



Vertical diameter 30 



Horizontal diameter 38 



Length of spine, incomplete 750 



Probable length when complete. . 950 or 1000 

 Antero-posterior diameter of spineatbase. 24.5 

 Transverse diameter of spine at base .... 19 

 A lumbar vertebra : 



One incomplete lumbar spine 540 



Length, bottom line of centrum of a lum- 

 bar 36.5 



Anterior face of same : 



Vertical diameter 45 



Horizontal diameter 36.5 



Sacral vertebrae : 



Length, bottom line of centrum of — 



First vertebra 32 



Second vertebra 34 



Anterior face of centrum of first sacral : 



Horizontal diameter 33 



Vertical diameter 37 



Posterior face of centrum of second sacral : 



Horizontal diameter 38 



Vertical diameter 29 



An anterior caudal : 



Length, bottom line 22 



Anterior face : 



Vertical diameter 36 



Horizontal diameter 35 



Posterior face : 



Vertical diameter 35 



Horizontal diameter 39 



A median caudal : 



Length, bottom line 22 



Length at level of neural canal of same. . . 31 

 Anterior face : 



Vertical diameter 27 



Horizontal diameter 24 



Posterior face . 



Vertical diameter 28 



Horizontal diameter 21 



Length of femur 263 



Width of head 77 



Width, lower end loi 



