118 



THE OSPREY 



T 



THE FORMATION OF THE BILL IN THE GENUS LOXIA. 



\VM. F. LEMMON, ENGLEWOOI), N. J. 



HE most distinguishing feature of the genus 2 and 5.) The nostrils and fossa- and also the com- 

 Loxiij, or Crossbills, is the formation of the missural point are covered with antrorse feathers, 



which are continuous to a greater 

 or less degree, over the base of 

 the culmen. This latter is well 

 marked for the whole length of 

 the mandible, and is dark bluish- 

 black in color. The dark area ex- 

 tends downward in front of, and 

 touching the fossae, to the rictus. 

 The lower mandible is straw col- 

 ored, darker at the tip, and there 

 is no appreciable difference in 

 s\,oU\'\\,c.^'>' color between the males and fe- 

 §"i-g.^ ((•p.ltwteij males, but this point can only be 



decided with fresh specimens. 

 The bill of /.. ctirvirostra minor is much stouter, al- 

 though no longer, than in the foregoing species, and 



bill Both mandibles are falcate, the upper one 

 usually coming out from the skull in a straight line, 

 the lower one deflected to one side, thus enabling the 

 points to cross. Often, however, the 

 anterior half of the upper mandible 

 is also deflected; the lower one is al- 

 ways so fron the />ase, the upper 

 never; at least this is so in the 120 

 specimens I have examined. 

 ^ , , . In about one-half of these the lower 



"^ ■5' ' mandible crossed on the right side of 



the upper, in the other on the left ; the sex making no 

 difference. These are the general characteristics of 

 the bill of this genus, but there is considerable varia- 

 tion among the species. 



The series of Loxia on which this paper is based, 

 is that of the American Museum of Natural History, the crossed portions of both 

 New York City, and consists of fourteen specimens mandibles more nearly equal 

 of lencopterci (White-winged Crossbill); ninety one in length. (See fig. 3 

 c. minor (American Crossbill), and ^^ 



On 



fifteen of c striddandi (Mexican 

 Crossbill). All the specimens of 

 leucoptera and c. minor from which 

 measurements were taken, were 

 collected in Eastern United States, 

 north of Delaware, and from New 

 Brunswick. Those of c. stricklandi 



account of the bill being so 

 much higher at the base, the 

 culmen and gonys are more 

 curved ; there is a variation 

 in this respect, however, one 

 specimen measuring 10 mm. 

 high at base, 16.5 mm. being 

 .^vj a-. Ve*c.<>(^«'-ti jhe length of the upper mandible; another, 8.5 mm 

 are from Arizona, all but one having been collected by at the base and 18. 5 mm. in length. These were both 





Dr. E. A. Mearns. 



Taking up L. letuoptera, I find that there is little, 

 if any, difference between the relative sizes of the 

 bills of the males and females. But on account of 

 the limited number of either sex 

 available, I cannot be positive on 

 this point. In the eight male 

 specimens, the longest measure- 

 ments were 18 mm. for the upper 

 mandible and 13 mm. for the 

 lower; these occurred in the same 



I 



■ I 



males, the bills of the fe- 

 males being slighter and 

 shorter. The vertical line 

 of the culmen in this spe- 

 cies, is either straight for 

 its entire length, or 

 straight for its posterior 

 half, and deflected either 

 to the right or left, for its 

 anterior portion. The 

 curvature occurs about 

 the centre of the culmen, the extremity of the man- 





bird. The averages were 16.5 



^''^"'°'" mm. and 11.5 mm. respectively, djble being therefore straight; in only one instance 



In this species the extremity of the upper mandible ^^^s it curved. The color is 



is convex on the side towards the tip of the lower, xnnch darker than in h-ucop- 



whether this be to the right or left of the former, /^;.,,, only the edges of the 



(See fig. I.) a peculiarity not ap- 

 parent in either the Red or Mexican 

 Crossbills. The tip of the lower man- 

 dible reaches about three-fourths 

 of the way to the extremity of the 

 upper. The anterior portion of the 

 under mandible is re-curved, while 

 the upper is de-curved for its cutir, 



commissural being light. 



The nostrils are feathered, 

 but the feathers do not al- 

 ways extend over the base 

 of the culmen, as in the fore- 

 going, and are not as dense. 



SVr'v 



^ 



i.4vlVl' 



§^?- 



In the case of the females 

 1^1^. \- c.nx.not. ^^^ ^.p^ ^j ^^^ nostril feathers seldom do more than 



length'; the rictus is nearly straight. Three points meet over the culmen and often do not touch at all. 

 which are also true of the other species. (See figs. The angle of the gonys is very prominent in all three 



