NATATORES. 421 



[186.] 6. Larus zonorhynchus. (Richards.) Ring-billed Mew-Gull. 



Genus, Larus, Linn. 



Ch. Sp. Larus zonorhynchus, tarso 2J uncias longo rictum rostri robusti torquati vix tsquante, dorso alisque 

 elongatis perlaceo-griseis, remigibus apicem versus cum rachidibus nigrescentibus ; spatio albo duorum exte- 

 riorum abbreviate. 



Ch. Sp. Ring-billed Mew-Gull, commissure of the stout, ringed bill rather longer than the tarsus, which mea- 

 sures 2^ inches ; mantle pearl-grey ; ends of the quills and their shafts blackish ; a short white space on the 

 two exterior ones. 



This Gull, which breeds in considerable numbers in swampy places on the 

 banks of the Saskatchewan, bears a close resemblance to our L. canus. Its 

 plumage is precisely the same, except that the white spaces near the ends of 

 the first and second quill feathers are one-half shorter, and in some specimens 

 there is none at all on the second*. It differs, however, remarkably in the size 

 of the bill, which approaches that of L. argentatoides, being much wider at the 

 base, more rounded on the ridge, and stronger every way than that of L. canus : 

 it has a conspicuous salient angle beneath, and is of a dutch-orange colour, with a 

 blackish ring near its tip. The icings are two inches longer than the tail. It is a 

 smaller species than Larns argentatoides of Bonaparte, and its nostrils are 

 shaped like those of L. canus. 



Dimensions 

 Of a male, killed on the Saskatchewan, June 7, 1&27. 





Inch. 



Lin. 



Inch. 



Lin. 





Inch. 



Lin. 



Length, total 



22 







Length from nostrils to tip . 



94 



Length of middle nail 



. 



+i 



,, of tail 



. 6 







,, of naked thigh . 1 



3 



„ of inner toe . 



. 1 



H 



„ of wing 



15 



3 



„ of tarsus . . 2 



5 



,, of hind toe 







2 



„ of bill above 



1 



9 



,, of middle toe . 1 



9 



,, of hind nail . 



. 



2 



,, of bill to rictus 



. 2 



7 













Another male is an inch shorter, and has a tarsus only two inches two lines long ; a third 

 is of intermediate dimensions. — R. 



* As in L. canus, all the quills have their extreme tips white, that of the first being a mere speck ; but of the 

 others, larger as they are more posterior. One specimen has, in addition, two small white spots near the tip of the 

 second quill feather. The markings on the quills of the Gulls vary with age, and can scarcely be used as specific 

 distinctions ; but they serve to assist in the diagnosis when taken in conjunction with the size and forms of the bill 

 and other members. — R. 



