Shufeldt: Birds from Bermuda. 377 



are very marked, but it will hardly be necessary to enter upon the 

 description of them here. I may say, however, that they are prin- 

 cipally to be seen in the proximal extremities of the bones in question. 

 As a matter of fact, the small Petrels just named are, with respect to 

 their osteology, very different birds as compared with the representa- 

 tives of either of the genera /Estrclata or Pjiffinus. 



In our present subject the humerus has an average length (both 

 sexes considered together) of 8.15 cms., its smooth shaft being but 

 very slightly curved; the convexity is on the anconal side and uniform 

 from head to distal end. 



The radial crest is distinctly triangular in outline, the superior 

 angle terminating in a distinct nib, the whole being bent palmad.^^ 



The ulnar protuberance or "inferior crest" is very conspicuously 

 developed, and, on the whole, bent toward the anconal side. It har- 

 bors, as usual, the pneumatic fossa, which is here deep and circum- 

 scribed. At its base may be discovered a few minute pneumatic 

 foramina, for nearly the entire skeleton of this Petrel is very largely 

 permeated by air, the usual " air-holes " being found at their usual 

 sites. 



The '■ incisure capitis " is well marked, while the articular part of 

 the head of the bone is not especially extensive. Points about it for 

 muscular insertion are defined by distinct, localized areas, marked 

 with varying definition in different bones, or rather in those that 

 belonged to different individuals. 



Distally, we see the large epicondylar or ectepicondylar process 

 standing out conspicuously from the side of the shaft, roughened, as 

 it is, for tendinal insertion. More centrally, and just above the 

 trochleje, is a deep, circumscribed concavity for the insertion of the 

 inferior brachial muscle. The entepicondylar process is particularly 

 prominent; and, indeed, this end of the humerus in the skeleton of 

 the bird under consideration has each and all of its characters un- 

 usually pronounced, though not any more so than they are found to 

 be in any of our Shearwaters of the genus Pnffiiuis. 



According to the variations due to age and sex, the length of the 

 idiia may run all the way from 8.6 cms., more or less, to 9.4 cms., 

 more or less, and is seen to be a strong and nearly straight bone, being 



1" This crest, the " crista superior "' of some authors, is low and rounded 

 in Oceanodroma. 



