162 PROCEEDINGS OF THE ACADEMY OP 



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in shape; the median series of them so broad as to nearly stretch across the 

 inner face of the tarsus. The inner toe is short, the tip of its small weak claw 

 hardly reaching to the base of the middle claw. The outer toe without its 

 claw is decidedly longer than the middle one ; but the much greater size of the 

 claw of the latter makes up the difference. The hallux is large and stout; a 

 straight, almost perfectly conical, moderately acute, claw. 



This genus is trenchantly separated from all others by the characters of the 

 bill ; in the lateral dilatation of which, the widely divaricating rami of the un- 

 der mandible, and the partially naked and distensible skin of the interramal 

 space, there is seen an approach to Prion of the Procellariince, and also to Pele- 

 canoides of the Halodrominse. The superior lateral mandibular laminae are so 

 wide and large, and so inflated, that they give a bulging convex lateral outline 

 to the bill. In the same manner the inferior mandibular rami rapidly diverge 

 from each other, their concavities presenting to the interramal space. In all 

 these points there is an interesting resemblarce to the genus Pelecanoides ; fur- 

 ther heightened by the broad ample rictus, loose dilatable skin of the floor of 

 the mouth, which is only partially feathered. These peculiarities are not shared 

 by any other genus of Procellariinse except Prion ; and leaving out of considera- 

 tion the widely diverse nostrils, the bills of Pelecanoides urinatrix and Daption 

 capensis are very similar in shape. 



The genus is of moderate size, of robust and compact form, and variegated 

 in the distribution of its colors. Its only known species is the type upon which 

 it is based, the well known D. capensis. 



Daption capensis (L.) Steph. 



Procellaria capensis, Linn., S. N. 10th ed. 1758, p. 132. Linn. S. N. 12th ed. 1766, 

 i. p. 213, No. 5. Linn. Amoen. Acad. iv. p. 240, and of other authors. 



Daption capensis, Stephens, Shaw's Zool. 1825, xiii. p. 241 : and of later 

 authors. 



Procellaria nwvea, Brisson, Ornith. 1760, vi. p. 146, No. 3. 



Procellaria punctata, Ellman, Zool. 1861, p. 7473. Cape Pigeon ; Black and 

 White Petrel ; Petrel Tachete" ; Pintado; Damier ; Pardela, etc., Voya- 

 ger's Vulgo. 

 This is one of the three species of Procellaria given by Linnaeus in 1758. It 



has remarkably few synonyms, in consequence of its marked characteristics. 



lis features are so well known that no mention of them is necessary in this 



connection, as the peculiarities of its bill have been elucidated under the head 



of the genus. 



Section PRIONEJE. 



The presence of laminated serrations along the inner edge of the upper man- 

 dible so trenchantly defines this group, that further characterization is unnec- 

 essary. A great similarity of color is found to prevail throughout. 



After elimination of the genus Halobzena on the ground of its square tail 

 and some other peculiarities, I find among the so-called Prions two very dis- 

 similar types ; which I consider as of generic import, and am therefore com- 

 pelled, however reluctantly, to separate under a new designation. 



The three genera here recognized may be thus distinguished : 



A. Bill compressed, its unguis large, its serrations moderate in extent, or con- 



fined to the base of the upper mandible. 



I. Tail truncated Halobsena. 



II. Tail graduated Pseudoprion. 



B. Bill excessively dilated, depressed, its unguis small and weak ; the serra- 



tions large and perfect to the extremity of the bill. 



III. Tail graduated Prion. 



HALOBSENA Is. Geoffr. 

 Procellaria sp. Gmelin, et auct. 

 Prion sp. Gray, Reichenbach, fide Bp. 



[May, 





