98 ME. G. BUSK ON THE ANCIENT OB 



keitloa) : — (1) that the two bones would appear to be of as nearly as possible the same 

 size ; (2) that on the anterior aspect of the shaft there is no appearance of the rounded 

 bulging observable in the middle part of that aspect in the humerus of B. hicornis ; 

 (3) on the posterior aspect in R. hicornis there is a strongly marked semicircular ridge, or 

 linea aspera, running upwards and inwards from the deltoid crest to the posterior border 

 of the articular surface of the head, no trace of any thing like which is visible in the 

 Gibraltar specimen ; (4) the rough muscular impression on the inner side of the shaft 

 is situated an inch lower down, and is larger in size in the Gibraltar bone. 



With respect to R. megarhinus, comparison with a magnificent perfect specimen of 

 the humerus of that species from llford (No. 23111, Brit. Mus.) shows that it was of 

 larger size, or, at any rate, thicker, having a least circumference of 9"'9. But the arti- 

 cular surface of the head is of pretty nearly the same dimensions, viz. 5"-3 X 4''-2 in the 

 antero-posterior and transverse directions. These dimensions, it should be remarked, are 

 identical, or nearly so, with those of the detached epiphysis, and but very little different 

 in the antero-posterior extent from those in the present specimen. 



I have not as yet met with a humerus of the smaller Thames-valley species retaining 

 the upper extremity. Tliere is none, therefore, with which the present specimen 

 could be compared, except as regards the least circumference of the shaft, which in 

 R. hemitoechus is about 8"-8, or an inch less than in the larger species. 



Another specimen is a small portion from about the middle of the shaft of a right 

 humerus, and corresponding in aU respects as to contour, condition, &c. with the same 

 part in specimen No. 7, and doubtless belonging to the same individual. Like the 

 bone just described, it appears to have been crushed and then recemented by cal- 

 cai'eous infiltration. 



Another important specimen is a nearly entire left radius, PI. XIV. tigs. 1, 2. 



This bone is 15"-0 long ; and the proximal end measures 2"-4 x 3"-8 in antero-posterior 

 and transverse diameters, and the distal end 2"-6 X 3"-9, whilst the least circumference 

 of the shaft (5 inches below the summit) is 5"-5. The perimetral index, therefore, of 

 the bone is about 'oGO. 



The principal, in fact the only difference of any importance between this radius and 

 that of R. hemitoecli us from llford, as represented in a perfect specimen of the latter 

 in Sir Antonio Brady's magnificent collection, happily now in the British Museum 

 (No. 45245), is that the former, with the same length, is rather the slenderer (in the 

 proportion of 12 to 13), the least transverse diameter of the shaft being in it 1"'95 and 

 in the llford specimen 2""1. But the antero-posterior diameter is the same in both, 

 viz. 1"'9. The least circumference in the llford specimen is 5""7, and its length 14"'5, 

 showing a perimetral index of •393. 



The proximal end of the Gibraltar bone measures 3"'75, and of the llford 3"-8. The 

 distal end in the former is 2"-5x3"-9, whilst in the llford bone it measures 2"-6x4"-2. 

 This difference, at first sight, is considerable, and might, justly perhaps, be regarded as 



