Mr. D. G. Elliot on the Trochilidse. 
47 
V- 9. Thaumatias nigricauda^ sp. nov. 
Top of head dull green ; nape and back shining grass-green. 
Throat and upper part of breast bright metallic grass-green; 
flanks dark purplish brown_, each feather tipped with metallic 
grass green; but the general appearance of the flanks is much 
duller and darker than the breast^ which lies above them like 
a shield. Centre of ahdomen_, thighs, and under tail-coverts 
pure white. Upper tail-coverts like the back, hut with a 
purple tinge. Tail has the two median rectrices black, with 
a very slight tinge of green in some lights, remainder hlue- 
hlack, edged with white on their tips. Wings purple. Bill— 
maxilla black, mandible flesh-colour, tip black. Total length 
inches, wing 2, tail 1^, bill f. 
Hab. Trinidad, British Guiana ( Verreaux); Cayenne ( Ver- 
reaux); Bahia (Berlepsch ). 
There is a Humming-bird from Cayenne which hears some 
resemblance to the T. tephrocephalus, but is smaller and more 
delicately shaped, has a diflPerently coloured tail and white 
under tail-coverts. I have seen a fair number of specimens 
all resembling each other ; and although I cannot place them 
satisfactorily with any of the described species of Thaumatias, 
yet I hardly feel myself authorized to definitely give them a 
new name with only my present materials to judge from. I 
will point out the diff'erences perceived by me, which per¬ 
haps may assist some ornithologist with a good series of 
specimens at his command to determine the proper place the 
bird should occupy. The breast and throat are a more golden 
green than that part of T, tephrocephalus ; but the ehief cha¬ 
racters which seem to separate them are the colour of the 
under tail-coverts and shape and colour of the rectrices. In 
the Cayenne bird the tail-feathers are narrow and slender, 
the median pair are golden green for their entire length, the 
remaining feathers have the entire inner webs, except the 
tips, black; the outer webs are metallic golden green, this 
hue not extending the entire length of the web on the outer¬ 
most feather, which is black on both webs below the tip. 
All the lateral rectrices are conspicuously tipped with bright 
