PHYLOGENY OF THE PALZOGNATHA AND NEOGNATHZ. 159 
b. Pterylosis of the Embryo and Nestling. 
The ripe embryo and the nestling Rhea americana appear to differ from the adult 
only in that the anterior portion of the apterion spinale is absent, and that there is a 
distinct oil-gland. 
I find no trace of an “ egg-tooth” in the ripe embryo, which I myself removed from 
the egg. This is also wanting in the embryo Dromeus and the nestling Caswarius. 
Concerning Dromeus, however, see p. 154. The late Prof. Jeffery Parker failed to 
find it in Apteryx at any stage of its growth. 
STRUTHIONIDA. 
STRUTHIO CAMELUS. 
1 have not been fortunate enough to secure either nestling or adults of Struthio; 
consequently I am obliged to fall back upon the published accounts of others. Nearly 
Fig. 3. 
A.—Lateral view of an embryo of Struthio, after Lindsay, to compare with Apteryx. Note the absence of a 
lateral cervical apterion. 
B.—Lateral view of an embryo of Apteryx australis, right side (after Parker), to show the pterylosis. Noto 
the distinct pteryla colli ventralis and dorsalis and the pteryla humeralis. 
all that can be gathered, moreover, concerning the pterylosis of the trunk of Struthio 
concerns embryos only. The wing of the adult Ostrich has been ably described by 
2a2 
