200 Annals of the Carnegie Museum. 



somewhat laterally comi)ressed. It bears a diminutive facet at its dis- 

 tal extremity, and appears as though it might have had in life a claw 

 there, which has been lost in my specimen. Nitzsch, who examined 

 many groups of birds to investigate this among other points, places 

 the Herodiones in the category of birds in which he discovered it to 

 be present. So on the authority of this eminent anatomist I believe 

 we may safely .say that our subject will be found to possess such a 

 claw. 



For its entire length the main shaft of this bone is very straight, 

 and such part of it as is free from contact with other bones above 

 and below, is subtrihedral in form and devoid of particular character. 



Showing a considerable transverse dilatation at its proximal ex- 

 tremity, the third metacarpal soon quits the shaft of the second to be- 

 come much smaller and rounder, being parallel to it, until within a 

 short distance of its lower end, where both are again connected by 

 bone. 



At the proximal extremity of this carpo-metacarpus, we find a 

 broad trochlear surface, contributed in the usual manner by the os 

 inagin/iJi, one of the free carpal bones in the wrist of subadult birds. 

 As in the majority of cases all the sutural traces of this union, have 

 with the growth of this heron become obliterated. 



Upon the palmar aspect, just below the superior convex margin of 

 this trochlear surface, at the head of the index metacarpal, we observe 

 projecting forwards a small stumpy process. 



The distal end of the carpo-metacarpus in the adult Ardca hcnn/ias 

 is almost entirely occupied by the two articular facets for index and 

 middle digits. A notch divides them. In the case of the first, the 

 proximal phalanx is a long bone (3.8 cm.), with a posterior blade- 

 like expansion. This latter is not very broad, being thick and un- 

 pierced by foramina, as we sometimes see it in the Gulls and other 

 water birds. A long, pointed subtrihedral joint succeeds this one, 

 which in turn seems to have a facet upon its distal extremity, either 

 for a claw or another minute joint, such as we find among the Ducks 

 and Geese, but in my specimen it is missing. The third metacarpal 

 supports a digit composed of a single sub-compressed, narrow phalanx, 

 nearly two centimeters long. 



Taken in connection with what Nitzsch has given us upon the sub- 

 ject, I believe the formula for the manus of the Herodiones will be 

 found to be pollex metacarpal, with a digit composed of two phalanges ; 



