ilTS EHEID^. 



Tujus, Rufinesque, Analyse, p. 70 (1815). Type. 



Pterocnemia, G. R. Gr. Hand-list, iii. p. 2, subgen. 24G0 



(1871) R. darwini. 



Pterocnemys, Sclat. ^ Salv. Nomencl. Av. Neotrop. 



p. 154 (1873) ( = Pterocnemia, Gr.). 



Range. Confined to South America. 



\Cf. Gadow, H., "On the Anatomical DiflPerences in the three Species 

 of Rhea" (P. Z. S. 1885, pp. 308-321).] 



Key to the Species. 



a. Metatarsus with transverse scutes through its 



length ; feathers greyish, more or less black- 

 ish on the head and neck, and with no white 

 tips. 



a'. Generally lighter ; skull broader americana, p. 578. 



h'. Generally darker, especially on the head ; 



skull narrower macrorhyncha, p. 581 . 



b. Metatarsus with transverse scutes on distal half 



only, feathered in front on the upper parts ; 

 general plumage brown, most of the feathers 

 with white tips darwini, p. 582. 



Note.— Rhea nana, much smaller than the other species, is 

 known at present only from the egg (P. Z. S. 1894, p. 654), and has 

 been described by Lydekker, Knowledge, xvii. 1894, p. 265 ; or in 

 ' Eevista del Museo de la Plata,' vi. 1894, p. 103 (with fig. of egg). 

 — Patagonia. 



1. Rhea americana. 



Nhandu-gnacu brasiliensibus, Marcr/r. Hist. Nat. Bras. p. 190 



(1648) ; Piso, Hist. Nat. Bras. p. 84, with fig. (1648). 

 Struthio camehis americanus, Ray, Syn. Av. p. 36 (1713). 

 Rhea, Moehr. Av. Gen. p. 55 (1752) ; Briss. Orn. v. p. 8 (syn. emend.) 



(Guiana ! and Brazil) (1760). 

 Struthio americanus, Linn. S. N. (ed. 10) i. p. 155, n. 3 (America 



Australi) (1758) {e.r Marcgrave and Piso); Hammer, Ann. du 



Mus. xii. pp. 427-433 (1808). 

 Struthio rhea, Linn. S. N. (ed. 12) i. p. 266, n. 3 (syn. emend.) 



(1766)* ; ? Molina, Sagyio Stor. nat. Chili, p. 232 (part.) (1782) ; 



Gm. S. N. I. 2, p. 727, n. 3 (part.) (1788) ; Hammer, Arm. du 



Mus. xii. pi. 39 (1808) ; Cuv. Regne An. i. p. 461 (1817) ; id. op. 



cit. 2nd ed. i. p. 496 (1829) ; Haughton, Pr. R. Irish Acad. ix. 



pp. 497-504 (myology) (1868). 



* I am almost sure that Struthio americanus, Lmn., and S. rhea, Linn., 

 founded on Marcgrave and Pise's descriptions, refer to the more northern species, 

 Rhea macrorhyncha, Sclat. ; but the change would now be rather too revolu- 

 tionary, and the creation of a new name for the Southern species perhaps 

 not very welcome ! The existence of the Southern form in South Brazil may 

 show that the more conservative ornithologists are right ! 



