NATURAL SCIENCES OF PHILADELPHIA. 161 



bill, which may be quite unaccompanied by corresponding differences as to 

 depth or width. The length of the nasal tubes, and the amount of turgidity, 

 and obliquity of truncation vary greatly. Differences in the depth and robust- 

 ness of bill are surprisingly great. 



I have never seen, of many specimens, any which were separable specifi- 

 cally from the typical form. But some individuals are so strikingly small, 

 that were it not for intermediate sizes, they might readily*be supposed distinct. 

 Upon this charncter a variety minor was founded by Bonaparte which has 

 been adopted by so accurate and cautious an ornithologist- as Dr. Schlegel. 



The only synonym of note I have met with is candidus of Peale, (1848.) The 

 original description of P. nivea by Gmelin speaks of black shafts of some of the 

 feathers. As Mr. Cassin justly remarks (Orn. U. S. Ex. Exped. 1858, p. 416) 

 should this ever.be found to characterize a species, the present must bear Mr. 

 Peale's name of Candida. I think it probable that dark spots or streaks would 

 be indicative of inmaturity ; but being unfamiliar with the plumage of very 

 young birds, I cannot speak with certainty. 



DAPTION Stephens. 

 Procellaria sp. Linnaeus, et Auct. 



Daption, Stephens, Shaw's Gen. Zool. xiii. 1825, p. 230. Type Procellaria ca- 

 pensis, L. 



The bill is much shorter than the skull, about three-fourths the tarsus, 

 rather more than two-thirds the middle toe, very stout, depressed, about as 

 broad as high for its whole length as far as the unguis, where it is suddenly 

 much compressed and higher than broad. Culmen is about straight or a little 

 concave from the nostrils to the root of the unguis, which latter is moderately 

 large, but not very convex nor much decurved. The lateral outline of the bill 

 is decidedly convex from its base to the unguis where the convexity suddenly 

 ceases; it is produced by the large, inflated and protuberant lateral lamina? 

 Just inside the cutting edge of- the bill is a series of oblique rugae, extending 

 the whole length of the bill. The lateral sulcus is well defined, running from 

 the base of the nasal case to the unguis, obliquely downwards and forwards ; 

 it is most distinct posteriorly, more shallow anteriorly, where it merges into 

 the depressed portion of the culmen. The lower mandible is perpendicularly 

 narrow, but horizontally is unusually broad, the rami widely diverging from 

 each other immediately from the symphysis. The gonys is short, scarcely con- 

 vex in outline, its angle small and inconspicuous. The interramal space is 

 very broad, in consequence of the wide divergence of the inferior mandibular 

 rami, and their mutual concavity. The rictus is exceedingly ample; and the 

 capacity of the fauces increased still more by the looseness and dilatability of 

 the enclosed skin. The feathers on the side of the lower mandible extend but 

 a short distance ; those in the interramal space only as far as a point opposite 

 the end of the nasal tubes; and by no means fill the space from side to side 

 when the skin is at all distended. 



The nasal case is very long for a component of the group JEstrelatesr, being 

 a third as long as the culmen. It is broad, depressed, a little more elevated 

 towards the apex, its dorsal outline a little concave and moderately carinated. 

 The orifice is subcircular, nearly vertically truncated, a little emarginated. 



The wings are of moderate length, about equal to the tail when they are 

 folded. The second primary is nearly as long as the first; the rest rapidly 

 graduated. The tail is rather short, contained about two and a half, times in 

 the wing from the carpus ; is moderately and very evenly rounded ; the rec- 

 trices being broad to their extreme tips. The upper tail coverts fall an inch 

 short of the end of the tail ; the inferior ones quite reach its extremity. 



But a very brief portion of the tibia is naked of feathers. The tarsus is much 

 shorter than the middle toe and claw, about equal to the inner toe ; very stout, 

 though much compressed ; covered externally with very small, irregularly sub- 

 circular plates ; which on the inner aspect are much larger and more regular 



1866.] 11 



