TUBINAKES 447 



superficialis. In CEstrelata brevirostris we first meet with 

 a recurrent slip going to the longus tendon and arising 

 from the brevis in front of the termination of its anterior 

 branch. The more typical tubinarian arrangement is seen 

 in CEstrelata Lessoni. We find here the characteristic 

 ossicle of the tendon of the brevis which is found in 

 so many Tubinares, and which has been held by some to 

 be a character of much systematic importance in differen- 

 tiating the group — a character which Furbeingee thinks 

 has been 'overvalued.'' From this ossicle spring some 

 of the fibres of the extensor muscle of the fore arm ; it is 

 also the starting point of the recurrent tendinous fibres, 

 which unite the breyis and longus tendons ; these tendons 

 are, moreover, in close apposition for nearly the whole of 

 their course — itself a characteristic feature of the Tubinares. 

 In Ossifraga and in some other genera there are no 

 ossicles, but the tendons are highly complicated. In some 

 petrels — for instance, in Diomedea exsulans — the wing sesa- 

 moid is double, and in this bird also there are considerable 

 complications of the various tendons. While, therefore, we 

 cannot define the petrels by the arrangement of the tendons 

 of the tensores, as is sometimes possible, it is evident that 

 we have what might be expected in a large and important 

 group — a very considerable series of modifications of these 

 organs. No petrel has, strictly speaking, a biceps slip, and 

 the biceps itself, though perfectly normal in origin and 

 insertion, has much more largely degenerated into tendon 

 than is usual for this muscle. There is, however, a curious 

 modification of this muscle in Pelecanoides and in a few 

 others. Here the coracoidal head alone forms the muscle ; 

 the humeral head goes entirely to the tensor patagii longus ; 

 this slip is, therefore, as Forbes remarks, ' functionally a 

 biceps slip.' Something apparently representing the true 

 biceps slip is occasionally found in the Tubinares. In a 

 few there is a tendon derivable from the humeral head of the 



' Justly, as it is found not only among the Steganopodes, which may be 

 fairly regarded as allies of the Tubinares, but also in so remote a type as 

 Merops ! 



