PAL^OMASTODON PAEVUS. 165 



seen that the deltoid ridge (d.) formed a prominent oblique crest continued up to the 

 greater tuberosity. The coronoid fossa (c./.) is wide and moderately deeply concave; 

 the olecranon fossa is large and deep, particularly on the outer side. The outer and 

 inner (i.e. and o.c.) condyles are both fairly prominent, the latter projecting considerably 

 backwards. The supinator ridge {s.r.) is short, much shorter relatively than in the 

 humerus of P. beadnelU described above. The articular surface is divided by a broad 

 groove into an inner larger (tra.) and an outer smaller portion (tr.o.). The former 

 bears a slight ridge which marks the separation of the surface for the radius from 

 that for the inner portion of the ulna. The bone, as a whole, is very thin-walled and 

 lightly built — a circumstance that may account for the extreme rarity of bones of 

 Palceomastodon. The chief points by which this humerus diifers from that of Elephas 

 are : (1) the greater tuberosity is larger and rises more above the head ; (2) the 

 supinator ridge is very much smaller, so that the distal portion of the bone is less 

 expanded; 



M. 8889. Plaster cast of the above specimen. Made in the British Museum. 



C. 8063. A similar right humerus wanting the proximal end. 



M. 8890. Plaster cast of the above specimen. Made in the British Museum. 



The dimensions (in centimetres) of the above humeri are : — 



0. 8881. 0. 8063. 



Length 45-2 43-3+ 



Width of head 9 



,, of shaft at narrowest 5'7 5-4 



„ lower end at widest 13'8 13 + 



„ distal articulation 9'8 10 



C. 8028. Nearly complete right ulna (text-fig. 57). The olecranon (ol.') is large, greatly expanded 

 at the end, and projecting strongly towards the inner side ; it does not rise above the 

 upper angle of the articulation. This latter is triradiate in form; the upper lobe 

 projects strongly forwards, while of the lower two, the outer has a straight anterior 

 border, beneath which is the elongated facet (»'.s.) for the upper end of the radius; 

 the inner is oval in outline and seems to have little or no contact with the radius. 

 The whole shaft of the bone is curved backwards ; it is triangular in section, the anterior 

 face being deeply concave from side to side near its upper end {r.g.) Distally it 

 widens out somewhat, but the epiphysis having been lost, the distal articulation cannot 

 be described. The whole ulna is practically that of a miniature elephant. The 

 dimensions (in centimetres) of the specimen are : — 



Length (without epiphysis) 38 



Width of articulation for humerus 93 



„ middle of shaft 4-8 



M. 8891. Plaster cast of the above specimen. Made in the British Museum. 



Jll. 8858. Upper end of left ulna. Presented by the Egyptian Government, 1 904. 



C. 8883. Right tibia (text-fig. 58). In form this bone is almost exactly similar to the tibia of 



P. beadnelU figured on PI. XVI. fig. 4. In the proximal articulation the inner facet (i.) 



