48 
Mr. D. G. Elliot on the Trochilidae. 
metallic golden green. The bill is red, tip black. This bird 
is about the size of T. tobaci, but the tails of the two are 
entirely different. I have compared it also with the type 
of T. maculicauda, and find the tail-feathers are about the 
same width and length as the rectrices of that species ; and 
in certain points of coloration the two resemble each other 
more closely than any of the other members of this genus; 
but I do not think they belong to the same species. Should 
the bird eventually be ascertained to be distinct, it might be 
known as 10. Thaumatias nitidicauda. 
' f - 11. Thaumatias chionurus. 
Thaumatias chionurus, Gould, Mon. Troch. v. pi. 300; id. 
Intr. Mon. Troch. 8vo ed. p. 153. 
Hab. Costa Rica. 
This pretty species, first described by Gould (/. c.), is a 
native of Costa Rica. In the colouring of the tail it differs 
greatly from all the species of Thaumatias, so much so that 
the term Elvira, proposed for it by M. E. Mulsant, does not 
seem to be altogether needless. A slight difference in the 
coloration of the sexes also separates it from the members of 
this genus. For the present, however, I retain it among 
the species of Thaumatias. There is no difficulty with its 
synonymy; and it cannot be confounded with any of its 
relatives. 
A- 12. Thaumatias tephrocephalus. 
Trochilus tephrocephalus, Vieill. Nouv. Diet. Hist. Nat. 
xxii. p. 439 (1818). 
Ornismya albiventris. Less. Hist. Nat. Ois.-Mouch. p. 209, 
pi. 76. 
Thaumatias albiventris, Gould, Mon. Troch. v. pi. 301; 
id. Intr. Mon. Troch. 8vo ed. p. 153. 
Hab. Brazil, Santa Catherina (Boarder); Delta of the 
Amazon (Gould). 
• Mr. Gould, in his monograph, gives as a reason for adopt¬ 
ing Lesson^s name of O. albiventris for this species, that M. 
Bourcier told him VieilloEs type of T. tephrocephalus was in 
a very bad state, and the feathers of the head much worn 
