NATURAL SCIENCES OF PHILADELPHIA. 137 



The first of these genera, after the fusion with it of those of Bonaparte 

 already adverted to, is quite an extensive one, coraprisinjx more species than 

 any other of the family. In this paper I enumerate eighteen, which appear 

 to have just claim to recognition. At the same time some of them, as I inti- 

 mate, may not he valid, while I am quite willing to believe that there may 

 exist good species of which no cognizance is here taken. 



.ESTRELATA Cones, [emend, ex Bp.] 

 Piocellaria sp. Auctorum. 



Dnption sp. Stephens, Shaw's Gen. Zool. xiii. 1825. 

 PuJjUnus sp. Webb and Berthelot, Av. Canar. 1836—44. 

 0>:si/raga sp. et Tlialassoica sp. Reichenbach, Sj'st. Av. 

 u-Estrelala, Bonap. C. A. 18.55, ii. p. 188. Type Pmc. ha'sitata, Temm. 

 Cookilarin, Bonap. C. A. 1855, ii. p. 190. Type Proc. Cookii, Gray. 

 Ptcrodroma, Bonap. C. A. 1855, ii. p. 191. Type Proc. macro/jtrr", Smith, 

 Buhveria, " Bp. 1836." (Gray.) Bp. C. A. 1856, ii. p. 194. Type Puff, col- 



umbinns, Webb and Berthelot. 

 Rhantiste.'t, Bonap. Compt. Rend., April, 1856, xiii. p. 7G8. Type Proc. Cookii 



Gray. (Not of Kaup, 1829, the type of which latter is Proc. glacialis, 



Linn.) 

 Cl:s. — Bill about as long as the tarsus ; very stout ; compressed ; higher 

 than broad throughout ; lateral outlines nearly straight, converging to the 

 much compressed unguis. Unguis particularly large, strong, its upper out- 

 line very convex, its tip greatly decurved ; arising almost immediately from 

 the end of the nasal tubes, leaving but a very brief and quite concave culmen 

 proper. Lateral element of the bill very strong ; rising high up at the root of 

 the nasal case ; somewhat inflated throughout ; and with a strongly convex 

 Inferior border ; which with the great decurvature of the unguis produces au 

 extremely sinuate commissure ; outline of lower mandible nearly straight ; of 

 gonys a little concave ; eminentia symphysis well marked. Sulci on both 

 upper and under mandibles distinct. Nasal tubes of moderate length, eleva- 

 ted, conspicuous, not carinated, dorsal outline about straight, apex more or 

 less vertically truncated, orifice subcircular, each naris oval, separated from 

 its fellow by a thin vertical portion which comes well forward. Interramal 

 space narrow, fully feathered. Wings comparatively longer than in racst 

 sections, surpassing the tail when folded ; pointed ; but the second primary 

 nearly as long as the first. Tail long, and much graduated ; sometimes almost 

 cuneate, usually much rounded; the reetrices quite broad to their tips. Feet 

 of moderate size ; tarsus moderately compressed, with the ordinary small 

 subhexagonal reticulations ; about as long as or a little less than the middle 

 toe without its claw. Outer toe rather surpassing the middle ; with its claw 

 about equalling the middle andchuv. Tip of inner claw reaching base of middle 

 one. Hallux short, sessile, conical, acute, elevated. (Tf moderate and rather 

 small size ; bicolor, or nearly so ; in youth nearly unicolor. 



The genus yEsfreUita as thus defined is quite an extensive one, comprising 

 a larger number of species than any other of the family. In its geographical 

 distribution, it is essentially southern and antarctic ; only a very few of the 

 eighteen or more known to compose it being found in north temperate lati- 

 tudes. The numerous species all agree in certain points which separate them 

 from others ; the princif)al of which is the large size and great convexity of 

 the unguis of the bill: which begins to rise almost immediately from the 

 nasal case. Other peculiarities will be noted in the above diagnosis ; which 

 have caused the species to be put in intimate relation to each other when col- 

 located even by those writers who recognize but one, or at most three or four 

 genera of Procellariime, 



Taking the hxsitata as the type of the genus, we find that most of the 

 species, — Lessoni, ro^trata, etc. agree entirely with it : while some others, 

 e. g. Cookii, diuer in being smaller and more slenderly built, with rather less 



1866.] 



