The Zoologist— July, 1870. 2209 



but the bill, which is of a radically different formalion, as will be im- 

 pressed upon the mind by a perusal and comparison of the descriptions 

 given under head of these species. Tetraculus requires no special 

 comparison with cristatellus or with camtschaticus for the substantia- 

 tion of its distinctness. S. Cassini of this paper is the most closely 

 allied species, and might just possibly be confounded by a careless or 

 ignorant observer. The differences will be found under head of the 

 latter. 



The diagnostic points of this species lie chiefly in the small size 

 and peculiar shape of the bill, the length of the wings (proportionally 

 greater than in any other species of the genus), and the greater length 

 of the feet and toes. The wings, tail, feet and toes are about of the 

 same absolute dimensions as those of cristatellus, although tetraculus 

 is rather a smaller bird. The various shades of the dark colour of 

 the plumage are produced by admixture of black, brown and gray: 

 there is no pure cinereous or plumbeous on any part of the plumage. 



This is a species which entered at a very early day into ornitho- 

 logical literature, notwithstanding which it has not a single accredited 

 synonym. Its claims to recognition as a valid species, distinct from 

 cristatellus, have not been impugned, except by the learned Director 

 of the Museum of the Pays-Bas. It has been the occasion of no 

 confusion or conflict of opinion among writers, except in those few 

 instances in which it has been erroneously supposed to have furnished 

 the subject of Audubon's plate of cristatellus. The most cursory 

 examination of the plate will convince the mind upon this point. 

 Mr. Pennant, in virtue of his "dusky auk," which is this species, 

 would have been entitled to the proprietorship of the bird, had he 

 given it a binomial name ; but as it is. Dr. Pallas stands as its lawful 

 sponsor, having christened it Alca letracula in 1769. 



Simorhynchus Cassini, Cones, n. sp. — Typical and unique specimen, 

 No. 46,564 of the Smithsonian Museum ; a male (adult ?) collected 

 August 3, 1866, at Ounimak Pass, Russian America, by W. H. Dall. 



Bill very small and short, only half as long as the tarsus ; extremely 

 compressed, being hardly more than half as wide as high at the base; 

 its height at base three-fourths the length of culmen ; lateral aspect of 

 the bill nearly triangular ; culmen regularly lightly convex in outline ; 

 rictus perfectly straight; gonys almost straight, ascending; tip of bill 

 rather obtuse ; no tubercles, sinuosities or other irregularities of surface 

 or of contour. Nasal fossae well marked, oval in outline, reaching the 

 culmen at its base, separated by a ridge from the commissural edge of 



SECOND SERIES — VOL. V. 2 L 



