An almost Perfect Skeleton of Pareiasaurus semdens. 133 



in the same plane as the pubis and ischium, the two sides when 

 together and in contact witli the sacral ribs form a large irregular V. 



The ilium resembles fairly closely the ilium in the skeleton of 

 P. boiiii. The crest is directed considerably outwards in front. 

 Appreciably more than half of the acetabulum is formed by the 

 ilium, and there is a prominent muscular ridge above the articu- 

 lation, as in P. haini. The ischium forms a little more than two- 

 thirds of the lower part of the pelvis. In the drawing a dotted line 

 shows what is believed to be the division between the ischium and 

 the pubis. The ischium forms about -llOm. of the symphysis. Its 

 posterior border then passes upwards, backwards, and outwards for 

 a distance of about •200m., where it forms a well-marked tuberosity. 

 With the exception of the large thickening, which forms the inferior 

 and posterior border of the acetabulum, the surfaces of the ischium 

 are moderately flat. The pubis forms about one-sixth of the 

 acetabulum. Immediately below the articulation with the ilium 

 the pubis broadens out to form an enormously thick pelvic brim. 

 This anterior portion passes almost directly downwards, and forms 

 a broad, flattened tuberosity which is about "OSOm. from the surface 

 of the main part of the pubis. This peculiarly thickened and bent- 

 down lip of the pubis resembles to some extent the corresponding 

 structure in P. haini. In the present skeleton it has the appearance 

 of being a distinct ossicle — a pre-pubis, but I am of opinion that it 

 is merely a portion of the pubis. Immediately behind this lip is the 

 pubic foramen, which passes upwards behind the acetabulum and 

 opens on the inside immediately below the ilio-pubic suture at a 

 point about -QGom. behind its anterior end. The symphysis is 

 exceeding strong, measming •230m. in length, and "OSSm. in 

 thickness at its middle. In front the pubes form near the middle 

 line a thin little anterior expansion. 



This well-preserved specimen settles beyond dispute one or two 

 points which Seeley has raised in his discussion of the pelvis of 

 P. haini. The pubis does not in the slightest degree extend on the 

 inner face of the ilium, nor does it form any articulation with the 

 sacral ribs as Seeley thinks possible in P. haini ; while there is no 

 indication, as Seeley believes there is in P. haini, of a "median 

 ventral ossification or a backward prolongation of pubes " preventing 

 the ischia from taking part in the median symphysis, and it is 

 manifest that Seeley has been misled by the crushed appearance of 

 the specimen he studied. 



The following are some of the principal measurements of the 

 pelvis : — 



