330 



NEW YORK STATE MUSEUM 



perforations at its base (two in number) being minute, and the 

 elongated tubeicles for the insertion of the tibialis anticus muscle 

 being double. Distally, the trochleae are powerfully developed ; 

 the middle one being the lowest upon the shaft; the outer one 

 next ; and the inner one the highest and holding the most posterior 

 position. The foramen, in the anterior sulcus between mid and 

 outer trochlea, is present. The bone has a length of about 10 cen- 

 timeters ; and about 9.3 centimeters in Chen h. nivalis; only 

 7.5 centimeters inAnser albifrons; and 6.2 centimeters in 

 Dendrocygna autumnalis. 



In all the North American geese and tree ducks (Dendrocygna) 

 the phalanges of the anterior podal digits are more or less well 

 developed; not so well so the hallux, nor the free first metatarsal. 

 The distal moieties of the ungual joints are sharp and curved ; in- 

 cluding these, the foot has the usual phalangeal formula of ordi- 

 nary birds, viz: two, three, four and five joints to one, two, three 

 and four toes respectively. Of the anterior basal joints, the middle 

 one is the stoutest ; the inner one the most slender ; and the outer 

 one holding an intermediate place in this respect. They all 

 have the usual characters of these bones as seen in anserine 

 birds generally, being uncompressed in any special direction, 

 and with the usual kind of anterior and posterior articulations. 

 Measuring from base to distal ends these joints have the following 

 respective lengths in Branta, viz : outer toe, basal joint 3.2 centi- 

 meters, next 2.2 centimeters, next 1.8 centimeters, next 1.8 centi- 

 meters, and chord of claw 1.1 centimeters; middle toe, basal joint 

 4 centimeters, its next joint beyond, 2.8 centimeters, next, 2.4 

 centimeters, chord of claw 1.4 centimeters; inside toe, basal joint, 

 4 centimeters, next 3 centimeters, and chord of claw 1.3 centi- 

 meters; basal joint of hallux, 1.7 centimeters, and the chord of its 

 claw .8 centimeters. Similar proportions relatively, and similar 

 characters are to be found in the skeleton of the feet of Anser, 

 Chen, and other geese. I have not these bones complete for Den- 

 drocygna autumnalis, but it is very likely the structure 

 of the skeletal part of the foot is very much the same in that genus, 

 as such of the bones as are in my possession would seem to indicate. 



OSTEOLOGY OF THE CYGNINAE 



This group, as has already been stated above, is made up in North 

 America (so far as is at present known) of the genus Olor, con- 

 taining the three species O. cygnus, O. columbianus and 



