360 Annals of the Carnegie Museum. 



ramal vacuity is reduced to a mere hair-like slit, and so on. It 

 measures in extreme length 5.9 cms., and so belonged to a larger bird 

 than P. parvus. 



Os furcuhim is of the U-shaped pattern, the clavicular limbs being 

 slender and of nearly uniform caliber throughout their lengths. 

 There is a faint hypocleidium on their somewhat thickened union 

 below; it is situated posteriorly and amounts to little more than a low, 

 thin line of bone. The free posterior extremities above are drawn 

 out into sharp-pointed endings, and there is an articular facet on the 

 outer side of each at a few millimeters' distance, posterior to the 

 apex. Such a fourchette is well seen in my figure of Proccllaria 

 cooki; but in this species the free extremities are not drawn out so 

 far, and the articular facets for the coracoid is better marked (PI. 

 XXIV, fig. 17). Compare figs. 61, 62, 68, 69, 70, 78. and 79 of 

 Plate XXVI. 



There is a perfect coracoid (left) of Puffinus parvus in the McGall 

 collection (fig. 92, PI. XXVII), which presents all the characters of 

 that bone as we find them in any coracoid of a typical Shearwater. 

 The axis of its shaft measures 2.2, cms., and the transverse diameter 

 of its sternal extremity 1.55 cms. There is a conspicuous precoracoid 

 process that exhibits a foraminal perforation at its lower part near 

 the shaft. The latter is non-extensive and much compressed antero- 

 posteriorly. With the somewhat prominent acromium, the precora- 

 coid forms, mesiad, a vertically elongate valley of considerable extent, 

 opposite which, on the other side of the bone, the glenoid cavity is 

 seen to be elongated vertically and very shallow. 



In the collection of the American Museum of Natural History there 

 are two fragments of a sternum which evidently belonged to this 

 extinct Shearwater. These fragments consist of the anterior portion 

 of the bone, and a large part of the left half of the sternal body. 

 They did not belong to the same individual, though to one of similar 

 size ; both were adult birds. Barring the difference in size, this 

 sternum of Puffinus parvus possessed a form very much like the 

 sternum as we find it in Puffinus major (see PI. XXIII, fig. 38). 

 The manubrium is small and peg-like, and the " coracoidal groves" 

 meet mesially. Ventrally, the thoracic concavity is unusually deep 

 and capacious, a single pneumatic foramen being present in the middle 

 line well within the anterior border of the bone. As usual in Puf- 



