Pterylography of the Hoatzin. 



347 



posed of long and fairly well-developed feathers ; on the 

 inside of the leg they are smaller and have a discontinuous 

 vexillum. 



Pt. uropygii (PI. IX. figs. 1,3, Pt.u.). — A large, thick, 

 hrush-like tuft of downy feathers surmounts the oil-gland. 



Fig. 1. 



A.sjf. 



Cr 



T.m 



Wing of Opi&thoeomus, extended. 

 Left wing of Opisthocomus (adult), showing the form when fully extended. 

 The proximal portion of the vane of the remiges and major coverts 

 has been removed. A.sp. Ala spuria; C.r. Carpal remex ; C. Cu- 

 bitals ; T.m. Tectrices majores ; V.t.m. Ventral tectrices majores; 

 T.md. Tectrices mediae (cut short) ; Pn. Parapteron ; P. Primaries 

 (metacarpo-digitals). 



whilst its base is encircled by a ring of down-feathers having 

 a large aftershaft. 



Pt. alaris (woodcut, fig. 1). — Remiges : — Metacarpo-digitals 

 (primaries) 10. Cubitals (secondaries) 11. Quintocubital, 



As will be seen in the figure, the remiges are of great length 

 relatively to the length of the limb ; the longest remex of both 



