8(^ 



1 



The anterior and lateral portions ot the piibes are very thin, as are also 



the median posterior portions of the ischiadic plates. The pubic bones are 



thickest on tiie posterior margin ; they present a downward-projecting median 



convexity near the anterior end. Depth of" the articular face, 2 inches 8 



lines. 



» 

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



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

 large mass of matrix, which fortunately protected and accompanied it. This 

 presents a transverse tliickening extending across it, and continuous with the 

 posterior margin of tlie clavicles. A median longitudinal thickening extends 

 from this to the anterior emarginatiwi, embracing in its angle with the trans- 

 verse a shalbw concavity. The posterior projection, which is continuous 

 with the median part of the ischia, is strongly detlexed behind the transverse 

 rib, and is continuous with the basinlike concavity formed l)v the united 

 pubes. The glenoid surface of the pubes is a sigmoid, while that of the 

 ischia is regularly convex. The articulation of the ilium nas been exclusively 

 with the former. 



Of the pleura])ophysial portion of the two arches nothing appears to be 

 preserved except two lateral symmetrical long bones. One was found em- 

 bedded in the mass carrying the pelvic arch, and they articulate well with 

 the pnbes ; but the articular extremity is too short to articulate with ischia at 

 the same time. Though they resemble the inferior view of the ])rocoracoids, 

 they represent the ilia oi' Plexioaaurus. The head is subdiscoid, rather Hat, 

 slightly j)rojecting eccentrically with a ligamentous pit. The articular surlacc 

 is very oblique to the axis of the shaft, and is separated from the surtiice by 

 a marked angle all round. Nothing like a trochanteric ridge is appai-ent in 



this bone. 



Measurements. 



iDcbes. Lines. 



Length iu tbo middle of the curve 9 9 



Diameter jit the head 3 :S 



Diameter, distally, on the; curve (i 



Dianictor, distally, straight 4 



The shaft is flattened cylindric : much flattened nearest the proximal 

 extremity. The latter is very oblique to the shaft, and slightly convex neai- 

 the proximal margin. 



The end of the muzzle preserved includes also the symphysis and parts 

 of the rami of the mandible. '^I'lic ])!nts have been crushed together, ami \\\v. 



