154 ME. W. P. PTCEAFT ON THE MOEPHOLOGT AND 



those described by myself in the Tinamous [8i] i. The young of Casuarius bear traces 

 of similar denticles. 



Podotheca. — ^The acropodium is made up of small reticulate plates which gradually 

 fuse to form ten large transverse scutes, covering its distal third. These are widest in the 

 middle of the series. The border region, between the acrotarsiura and the acropodium, 

 is clothed with tiny granulate plates ; these extend downwards so as to clothe the 

 proximal half of both outer and inner toes — the remaining region of these, like the 

 whole of the middle toe, being protected by large scutes. The inner claw is not 

 elongated as in Casuarius. The planta is covered with small reticulate plates. 



It is interesting to note that the podotheca and the cere are mottled with black 

 pigment, so as to carry out the general scheme of coloration which characterizes the 

 feathers. This mottling is most distinctly marked in a ripe embryo (fig. 2 b). In a stage 

 earlier than this, and in the nestling, they are not nearly so distinct. 



The Uropygmm is distinctly traceable in this nestling : in the ripe embryo it is 

 much more easily demonstrable. Here it is represented by a small rounded oval mass 

 partly embedded in the skin and lying immediately above the cloacal aperture, as in 

 Apferyx. 



Neither in this nestling nor in the embryos is there any trace of a separate, detachable, 

 egg-tooth, as is found in the Neognathce ; but the region of the beak in which this is 

 usually borne is, in the embryos, produced into a small conical elevation of a whitish 

 colour. Perhaps we should be correct in regarding it as a non-detachable egg-tooth 

 becoming absorbed after hatching. In the Neognathce it is detachable, and falls off 

 after this event, 



E.H E I D^. 



Rhea ameeicana. 

 Apteria : — 



A. spinale. — In one adult and a three-months old nestling this was divided into two 

 portions — more or less distinctly — an anterior and a posterior ; thus recalling the form 

 of this tract in some Tinamous, e. g. Calodromas elegans. The anterior space was 

 cordiform in shape, with its base towards the head. Its greatest width was nearly 

 2 in., its greatest length about the same. A more or less perfectly feathered area 

 of about 4 in. in length divided this from the posterior apterion which is continued 

 to the tail. It was at first about f in. wide, narrowed to 1^ in., contracting again to 

 1 in. for the rest of its course. In another adult and three-months old nestling the 

 anterior aptei'iou was very small. 



J'n other adults, and seven young birds ranging from embryos to half-grown 

 specimens, the anterior space was wanting. 



^ Figures in brackets refer to Bibliography at end of paper. 



