Embryos and N'esf/itti/s cy/Centropus sinensis. 655 



Stage 3 (figs. 4& 5, p. 661). I have also seen a very young 

 embryo of this species, in which prominent feather-papillse 

 occurred in three definite regions : — A double tract from each 

 side of the head immediately above the eye to the pygidium, 

 and in the areas subsequently occupied by the pt. huraeralis 

 and pt. femoralis respectively. The foot of this embryo had 

 not yet become zygodactylous. 



Fig. 1. 



yjt^u 



pf. ofivd. 



Nestling of CeJitropus sinensis, Stage 2. 

 -Dorsal aspect, showing the form of the pterylfe and apteria. 

 Compare the form of the pteryla spinalis with that of Stage 3, 



fig- ^■ 

 Fig. 2. — Ventral aspect, to show the incomplete pteryla ventralis in the 

 embryonic stage. 



Explanation of the lettering, 

 apt. coll. lat. = apterion colli laterale. 

 apt.sp. = ,, spinale. 

 pt. cap. = pteryla capitis. 



Stage 1. — The trichoptiles are now at the highest point of 

 their development. The longest, those on the head and back, 

 measure 30 mm., or about one-third of the total length of 



2 y2 



