REPORT ON THE ANATOMY OF THE PETRELS, 27 
found in the tendon of the superficial part of the ewtensor where it arises from the 
humerus. 
In Majaqueus (Pl. IV. fig. 7), Bulweria, and Puffinus the tensor patagu brevis 
(t.p.b.) tendon is not fused with the much broader and stronger tensor patagi 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 obscwrus) 
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 Gistrelata, and 
of somewhat smaller form; from it spring both tendinous fibres for the patagial tendon, 
and fleshy fibres for the superficial belly of the ewtensor (e.m.); from it also, or 
from the fibres of the last muscle, passes off a thin tendinous fasciculus (f) to the 
ulnar fascia. Proximad of this larger ossicle is a smaller, more circular, one (a’), which 
is developed in the more superficial of the twin tendons already described a little beyond 
its origin, where it plays over the supracondylar process. This second ossicle is very 
small in Bulweria. 
In the genera Pagodroma, Daption, Fulmarus, Thalasseca, Aeipetes, and Ossifraga, 
no bony nodules are developed, but the arrangement of these tendons at the elbow 
becomes very complicated. Their arrangement in Ossifraga, with which the others are 
almost identical, is represented in Plate IV. fig. 5. 
The tensor patagii longus (t.p.l.) tendon divides near the elbow into two parts, 
one continuing as the marginal patagial tendon, provided with the usual cushion of 
elastic tissue opposite the bend of the arm, the other receiving the much thinner 
tensor patagw brevis (t.p.b.). The united tendon so formed becomes somewhat diffused 
distally, and more or less fused with the superficial tendon of origin of the extensor 
metacarpi radialis longior (e.m.), from which it is continued onwards to the ulnar fascia 
by two well-defined bands. Between the most wristward of these and the marginal 
tendon of the patagium there is developed a narrow vinculum. 
In addition to this the main tendon of the tensor patagw which has a clear, well- 
defined edge on its humeral side, where it crosses the extensor muscle, sends a small 
special slip of tendon (t.p’.) to the deeper of the two bellies of that muscle. 
In the Diomedeinz the arrangement (Pl. IV. fig. 3) more resembles that of the 
Puftinese, as here also two ossicles are developed with nearly the same relationships to 
their surroundings as in that group. The tensor patagii brews (t.p.b.) is separate 
from the tensor patagi longus (t.p.l.) till near the elbow, the marginal tendon of 
the latter muscle having received, a little before, the very long and thin tendinous biceps 
slip (b.s.). 
The relations of the ossicles are very nearly as in Majaqueus (vide the figures), but 
