398 GEOLOGICAL SURVEY OF THE TERRITORIES. 



suggests a vertical head. They, however, are probably more or less dis- 

 torted, and the plane of compression changed. No well-defined distal 

 extremity of a rib can be made out, nor have anything like abdominal 

 ribs been preserved. 



The scapular arch is remarkable for its large clavicles (or procoracoids.) 

 As preserved, the latter are quite convex downwards, both antero-pos- 

 teriorly and transversely, while the coracoids are equally concave in 

 both directions. The clavicles have a remarkable external fiat projec- 

 tion, which is separated from the glenoid cavity by a deep sinus. The 

 glenoid cavity is bounded by an elevated ridge, which sends a branch 

 along the claviculo-coracoid suture to the precoracoid foramen. This 

 foramen is relatively of small size, and is a longitudinal oval ; the two 

 are separated by an isthmus composed equally of processes of clavicle 

 and coracoid. The coracoids are very thin except in a transverse por- 

 tion, which extends across behind the precoracoid foramina; a strong 

 elevated rib extends across the posterior face at this point. The outer 

 margin of the coracoid is thickened, rounded, and slightly concave. 



In. Lin. 



Greatest anteroposterior length scapular arch 33 6 



Greatest antero-posterior length clavicle 14 9 



Greatest antero-posterior length glenoid cavity. C 9 



Greatest antero-posterior length precoracoid foramen 7 3 



Transverse extent of claviculi 27 



Transverse extent of coracoidea 16 



From acetabulum to foramen 7 6 



The form of the posterior margin of the coracoidea is unknown, and 

 they are much broken on the inner margin. They may have been con- 

 siderably longer than in the accompanying cut. 



The greater part of the pelvic arch appears to be preserved. From 

 the obliquity of the median suture and from the form of the pubes, as 

 they are preserved on a large nodule of indurated clay, it is evident 

 that they have formed a boat-shaped support to the abdominal viscera, 

 with an obtuse keel on the median line below. The following diagram 

 will explain the relation of its parts : 



In. Lin. 



Greatest antero-posterior length 25 



Greatest antero-posterior length pubis 13 G 



Antero-posterior median length to notch of ischia 7 



Length coracoids behind notch 4 6 



Greatest width pubes 27 G 



Greatest width ischia 21 



The anterior and lateral portions of the pubes are very thin, as are 

 also the median posterior portions of the ischiadic plates. The pubic 

 bones are thickest on the posterior margin; they present a downward 

 projecting median convexity near the anterior end. Depth of the 

 articular face, 2 in. 8 lin. 



The superior surface of this arch was brought to light by the exer- 

 tions of my friends, B. Waterhouse Hawkins and William M. Gabb, who 

 removed a large mass of matrix which fortunately accompanied and 

 protected it. This presents a transverse thickening extending across 

 it, and continuous with the posterior margin of the clavicles. A median 

 longitudinal thickening extends from this to the anterior emargination, 

 embracing in its angle with the transverse, a shallow concavity. The 

 posterior projection which is ^continuous with the median part of the 





