NATURAL SCIENCES OF PHILADELPHIA. 183 



which his extensive researches in almost every department of Zoology so 

 justly entitle him. 



DlOMEDEA CAUTA Gould. 



Dlomedea cauta, Gould, P. Z. S. viii. p. 177. Id. Ann. Mag. Nat. Hist. xiii. 

 1844, p. 360. Id. B. Aust. pi. 40. Gray, Gen. Birds, (plate of bill), 

 and of authors. 



Habitat. From the south coast of Van Diemen's Land. 



A beautiful species having the colors of plumage of the melanophrys group ; 

 readily distinguishable from all other species by the following peculiarities in 

 the shape and color of the bill, and outline of the frontal feathers. 



The frontal feathers lie in a straight or slightly convex outline across the 

 base of the culmen, and then descend perprtidicularly to the commissure ; 

 forming a slight reeentrant angle on each side of the base of the culminicorn. 

 From exactly opposite their termination on the commissural edge of the upper 

 mandible those on the lower start, and descend in a straight line with a 

 slight forward obliquity, forming a very obtuse angle with those on the upper 

 mandible. 



The dorsal outline of the culmen descends from the forehead with a gentle 

 curve, to rise again on the unguis, but not so high as at the forehead. The 

 point of greatest concavity is opposite the middle of the bill. Basally the 

 culminicorn agrees with that of culminata and chlororhyncha, and differs from 

 melanophrys, in not widening behind the notnls, nor descending to overlap 

 their bases and meet the upper edge of the latericorn ; a uarro.v sub- 

 rectangular space thus left being covered only with soft skin. 



The latericorn is very broad throughout as compared with the culminicorn ; 

 i. e., the lateral sulcus is placed high up. The latericorn is exceedingly deep 

 at its base, running high up towards the sides of the ba>e of the culminicorn, 

 and, in consequence of the strong upward inflection of the commissure 

 towards its base, the sides of the under mandible are also very deep basally, 

 and run high up to form an acute angle with the feathers at the commissure. 



The nostrils present no discrepancies from other species of this group. 



"Bill light vinous gray or bluish horn color, except on the culmen where 

 it is more yellow, particularly at the base ; the upper mandible is surrounded 

 at the base by a narrow belt of black, which also extends on each side of the 

 culmen to the nostrils; base of lower mandible surrounded by a belt of rich 

 orange, which extends to the corners of the mouth." (Gould.) 



Chord of culmen 475 ; height at b-tse 1-90; width 1-25; height at unguis 

 1*25; from feathers ou lower mandible to the tip of its unguis 3-75. Tarsus 

 3-25 ; middle toe 5-00 ; outer toe 4-75 ; inner 4-25 ; wing 22-00 ; tail 10-00. 



The plumage is th it of melanophri/s even to the transocular dark fascia ; but 

 this in the specimen before me extends quite to the bill, which is not the case 

 in the numerous specimens of melanoplirys examined. 



A suffusion of the head and neck with pearly gray is doubtless indicative 

 of immaturity, as is the case with other species. 



This bird is superbly figured in Mr. Gould's and Mr. Gray's plates cited 

 above. The latter is an exceedingly accurate delineation of the bill. 



DlOMEDEA CULMINATA Gould. 



Diorncdea chlororhynchos, of Audubon's Works ; witness the type specimen it- 

 self. Lawrence, Gen. Rep. Birds, N. A., 1858, p. 822. (Excl. syn.) 

 Diomeiea culminala, Gould, Ann. & Mag. N. H. 1844, xiii. p. 361. Id. B. Aust. 

 vii. pi. 41. Gray, Gen. Bds., 1849, pi. 179. 

 This species in color of plumage is quite identical with chlororhyncha, and 

 the bill, in its general characteristics of shape, most resembles that of the 

 latter species. But the bird is much larger, stouter and heavier, as will he 

 seen by comparing the dimensions given. The bill in general terms may be 

 stated to be heavier and stronger, though not longer than that chlororhyncha ; 



1866.1 



