100 ME. G. BUSK ON THE ANCIENT OE 



in the Grays specimen. The os lunare from Grays, from its size, I should refer, at any 

 rate provisionally, to the larger of the two species found there, viz. B. leptorhinus 

 (B. megarhinus) ; but as I have not seen any specimen of the same bone belonging with- 

 out doubt to B. hemitmchus, I can only employ the smaller dimensions of the Gibraltar 

 bone as a doubtful argument in favour- of its belonging to that species. 



The other specimens appertaining to the anterior extremity are portions of five 

 metacarpal bones. Unfortunately these are all fragments of the lower end of the 

 bones only. They include the distal articulation, and in some nearly half of the shaft 

 of two right second and two left second metacarpals, together with a similar fragment 

 of the third right. To judge &om their dimensions, these bones would appear to have 

 belonged to two individuals, one considerably larger than the other ; but, except in 

 size, the corresponding bones do not appear to present any appreciable differences 

 whatever. The following dimensions, giving the antero-posterior and transverse dia- 

 meters of the distal articular end, will suffice to show their not inconsiderable 

 difference m size : — 



in. 



1. MC2 (fZ) 15x14 



2. MC 2 (s) 15 X 14 



3. MC2 ((^) 17x15 



4. MC2 (s) 16x15 



5. MC3 (cZ) 17x19 



In comparison with other species, it may be noted that the distal articular trochlea 

 in B. Ucornis (femur of same size) is 17 X 21, in B. hemitoeclms (Ilford) (mean) 16x20, 

 and in B. megarhinus, Grays, 2-1 x 2-5. These numbers afford additional evidence of 

 the close similarity between the Gibraltar species and B. hemitwcJius, and at the same 

 time of its distinctness from B. megarhinus. 



4. Hinder Extremity. 



The only clearly recognizable specimens belonging to the femur are (1) a fragment 

 consisting of about the upper third of the bone of the right side, and (2) a detached 

 third trochanter, with a portion of the shaft from which it springs, and, without doubt, 

 belonging to the same bone. 



(1) The larger portion (Pis. XII. & XIII.) presents the head considerably abraded on 

 the upper surface, the entire trochanter major and a portion of the shaft rather more 

 than six inches long below the head ; and on the inner border is the prominent tro- 

 chanter minor, the lower point of which is at a distance of 5"'6 below the lower border 

 of the articular head. On the anterior aspect (PI. XII.) the bone is much excavated 

 below the head and trochanter, which arches over it on the upper and outer part. 

 A slightly elevated ridge runs dii-ectly downwards from the outer border of the arti- 



