764 The American Naturalist. [September, 
other respects less so. The manus is not flexed so much, and 
consequently the ulnare has not been pushed so far outside the 
ulna. In this specimen, unlike the others, the two lobes of 
the ulnare are about equal in size, the distal one oval, the 
proximal wedge-shaped. The radiale retains its bilobate ap- 
pearance as described in stage I. Carpale IJ+III forms a 
lunate mass of fully developed cartilage about the head of 
metacarpal III. Carpale IV is slightly smaller relatively than 
in the previous stage; the digits are essentially the same. 
Stace V, (Fia. 5). 
In the specimens (fig. e) which forms the basis of this stage, 
the manus now assumes very nearly the form which it has in 
the adult bird. The radiale is irregular in shape and fitted to 
the distal end of the radius, the inner distale margin of the 
ulna and the approximate surface of carpal II-III. The dis- 
tal lobe of the ulnare is here at à minimum in comparison 
with the proximal lobe; it is now closely appressed to carpale 
IV which is wedged between it,and carpale III. Metacarpal 
II has approached metacarpale III and on its radial side is 
developed a large projection or “trochanter.” Its proximal 
phalanx is entirely cartilaginous, its distal one is just begin- 
ning to appear. Metacarpal III now bears three phalanges, 
the distal one not yet cartilaginous. Metacarpal IV has 
assumed a position parallel to metacarpal III, but is not yet 
united to it. Metacarpal V has approached metacarpal IV 
near its proximal end. 
SrAGE VI, (Fra. 6). 
In birds of this age (fig. f), carpales IT, III and IV have 
entirely coalesced, and, together with metacarpal II, form a 
solid socket into which fits the head of metacarpal III. 
Metacarpal II bears two phalanges; metacarpal III three, 
their distal phalanges being unequal. Metacarpal V now 
touches metacarpal IV and is not so near the proximal end as 
in earlier stages. 
AIR ED Um 
CPC Sab URDUN 
