146 On the Tarsus and Carjnis of Birds. 



tibia. This exception occurs in the kingbird, wliere these 

 two bones appear to unite Avith the tibia first, leaving a deep 

 intercondylar groove between them. 



Carpus. (See jjlate v.) In the fore limb or wing- 

 there are at least four carpal bones, two in the proximal 

 series, and two in the distal series. When more than four 

 carpals occur, as in the yellow warbler, and possibly in the 

 kingbird, the extra one is found on the radial side, and this 

 seems to be in accordance with wdiat obtains in the higher 

 vertebrates, wdiere we find on the radial side three carpals ; 

 the scaj)hoid, trapezoid and trapezium. 



In the proximal series of carpal bones, the scaphoid or 

 radiale is the largest, and is the first bone to appear in the 

 development of the carpus. This bone is always free. 



The cuneiform or idnare is smaller, and in most of the 

 species examined is found beyond the outer edge of the ulna. 



In Wilson's thrush, the bank swallow and yellow warbler, 

 it seems to anchylose with the outer distal end of the ulna, 

 so closely is it appressed to that region. On consulting Dr. 

 Elliott Coues in regard to the subject, he informed me that 

 two free carpals are always present in the adult yellow 

 warbler. As this bird when embryonic has an extra carpal 

 present on the radial side, it may be this one with the radiale 

 that makes up the two free carpals, 3^et o1)servations are very 

 limited in this respect; and until the contrary is proved, I 

 shall hold that the ulnare may unite with the ulna. 



In the distal carpal series is a bone which appears next in 

 development. Whether this represents the interniedium and 

 centrale, connate, or the third carpale (^magnum), I am not 

 able to say. It is always found at the base of the mid-meta- 

 carpal, to which it early anchyloses. This bone is quite 

 small, and lenticular in shape in Wilson's thrush, the chip- 

 ping sparrow, crow blackbird, eave swallow, bank swallow, 

 kingbird and yellow warbler, and large in the cow blackbird 

 and bluebird. 



In the kingbird an accessary carpal is seen near the third 



