FAUNA OF THE GOSAU FORMATION. 



663 



process was but little more than 1 \ centim. where widest, and became 

 somewhat narrower as it extended outward. 



Humerus. 



Both the right and left humeri are strong bones (PL XXIX. 

 figs. 1-3) which, previously to fossilization, had lost both proximal 

 and distal articular ends. They are of exactly the same length as pre- 

 served, and are mutilated in almost the same manner, the distal ends 

 especially being obliquely truncated from behind forward ; and they 

 show a subquadrate section. The right humerus is slightly the 

 more perfect ; and neither bone is distorted by pressure. 



The fragments are 8 inches long ; and, as preserved, the right 

 humerus is 4-j inches wide at the proximal end ; the left humerus is 

 4 inches wide ; the shaft is most constricted in the middle, where it 

 measures 1 T 7 ^ inch from side to side ; there is no corresponding con- 

 striction from back to front ; but in this position the anteropos- 

 terior measurement is 1^ inch. The bone widens distally ; but, as 

 preserved, the distal measurement from side to side is only 2 T ^- 

 inches. The proximal articular head was nearly in the same plane 

 as the distal end. The inner lateral outline is gently concave ; 

 the external outline is deeply concave, owing to the expansion out- 

 wards of the large thick deltoid process, which is bent at a consider- 

 able angle with^the shaft. The anteroinferior and postero-superior 

 outlines are both nearly straight, though very slightly concave ; and 

 they converge slightly from behind forward, owing to the slight distal 

 twist giving to the bone an appearance of thickening to that end. 

 At the distal end the shaft becomes flattened both in front and 

 behind ; and these surfaces are nearly parallel; and, where fractured, 

 the bone is here 1 T ^- inch thick on the outer side, and somewhat 

 thinner on the inner side. The remainder of the inferior surface 

 is anterior to, and makes a slight angle with, the subtriangular 

 flattened distal area. It also may be said to be a long triangle ex- 

 tending from the inner corner of the distal articulation forward to 

 the divergent elements of the proximal end (fig. 2). Nearly its whole 

 length is straight ; and its middle portion is more rugose with mus- 

 cular attachments than the rest of the bone : the markings have the 

 appearance of slightly impressed ovate pits, which extend for a length 

 of nearly 3 inches. This inferior area is defined by faint lateral 

 ridges, and proximally, beyond the muscular markings, becomes 

 somewhat deeply concave from side to side, and compressed towards 

 the superior aspect, so that in length it is convex. This area is a 

 little inflated on the inner portion, and terminates laterally in a 

 slight sharp ridge. The outer expanded wing has a well-rounded 

 margin. 



Superiorly the bone is highly convex from side to side (fig. 1), 

 though somewhat flattened on the inner and posterior side, and 

 also on the expanded external process, which is smooth and 

 slightly concave in length, and slightly convex from within outwards. 

 The upper aspect of the bone is divided into two portions by an 



