THE VOYAGE OF THE * CHALLENGER. 391 



In (Estrelata brevirostris (PI. XIX. fig. 3) the condition of things is 

 similar, but the patagial fan is more strongly developed, and the 

 tendinous superficial part of the extensor metacarpi is split, proximad of 

 the extensor patagii, one part arising superficially to, the other (e.m.*) 

 deep of, the prominent supracondylar humeral process. 



In the genus (Estrelata proper as represented by (Estrelata lessoni 

 (PI. XVIII. fg. 1), (Estrelata mollis, and an undetermined species the 

 arrangement differs considerably from that observed in (Estrelata brevi- 

 rostris t. The tensor patagii brevis tendon, which is more or less fused 

 above with the marginal tensor patagii longus tendon (t.p.l.), develops at 

 its junction with the superficial tendon of origin of the extensor (e.m.') 

 this being, as in (Estrelata brevirostris, double a small, elongated ossicle 

 (a) from which arise not only tendinous fibres some of which form a 

 patagial fan, whilst others join the marginal tendon directly but also a 

 number of muscular fibres which form the belly of the superficial part of 

 the extensor. The tensor patagii brevis continues on in the usual manner 

 to the ulnar fascia. No bony nodule, it is to be observed, is found in the Zool. Chall. 



tendon of the superficial part of the extensor where it arises from the Exp. vol. iv. 

 . pt. xi. p. 27. 



humerus. 



In Majaqueus (PI. XVIII. fig. 3), Bvilweria, and Puffinus the tensor 

 patagii brevis (t.p.b.) tendon is not fused with the much broader and 

 stronger tensor patagii longus, but is a distinct, very slight, slip, lying 

 between this and the humerus. 



At the elbow it joins the superficial ossicle (a), developed at the 

 junction of the tensor patagii with the extensor tendons. In Puffinus 

 (brevicauda and obscurus) this thin tensor patagii brevis is split below into 

 two slips, one joining the deeper of the twin tendons of origin of the 

 superficial extensor, whilst the other is inserted on the supracondylar 

 process. The ossicle is larger than the corresponding one of (Estreltita, 

 and of somewhat smaller form ; from it spring both tendinous fibres for 

 the patagial tendon, and fleshy fibres for the superficial belly of the 



t The condition above described as obtaining in (Esfrelata brevirostris was exactly 

 the same in all the specimens, eight in number, dissected. Unfortunately all these 

 were young birds, though the largest must nearly have attained its mature plumage, 

 and was probably able to fly. In other young birds in the group that I have examined 

 the disposition of these elbow tendons is always exactly the same as in the adults, and 

 even when these last develop ossicles here, such ossicles can be found, in a cartilaginous 

 condition, in quite young birds. I have no reason therefore to suppose that the differences 

 described here as existing between (Estrelata brevirostris and the other species of that 

 genus are due to any difference in age. 



[P. S. Since the above was written, Mr. R. Ridgway has been kind enough to 

 examine, at my suggestion, the skins of this species in the Smithsonian Institution, 

 and finds, as he informs me, no difference in the development of the ossicle between 

 this and the other species of the genus. The question, therefore, requires further 

 material to elucidate it.] 



