1044 The American Naturalist. [December, 
but are certainly of the same genus as tomentosus. If they are 
not C. cacti, they represent a new species exceedingly like it— 
a view of the case which seems wholly untenable. 
The conclusion, therefore, at which I arrive is that Coccus, as 
typified by C. cacti, is a genus very near to Hriococcus, and not 
by any means to be separated as a different tribe. Also, that 
the cochineal insect includes three or more closely allied spe- 
cies or races. It will be useful to consider the characters in 
detail. 
COCCUS L., Sign. 
Adult Female. 
Size.— Coccus cacti, according to Signoret, is from 6 to 7 mm. 
long. C. tomentosus, from Guanajuato, varies from 31 to nearly 
5 mm. in length. 
Shape.—The species are broadly oval; the keel seen by Sig- 
noret is more due to shrinkage in drying than anything else. 
C. tomentosus may be described as hemispherical, with the hind 
end a little pointed. 
Color.—A]l give the characteristic cochineal color, and so far 
as this 1s concerned, I see little difference. C. tomentosus placed 
in eaustie soda without heating, gives a beautiful reddish- 
violet color; on boiling, this turns bright crimson. This was 
observed in Guanajuato specimens; of Silao examples I noted 
that heated in caustic soda they gave a magenta color, very 
strong, which, by transmitted light, was bright violet, like log- 
wood staining. 
C. confusus, boiled in soda, gave a very fine, bright carmine. 
The under surface of C. tomentosus, where free from secretion, 
appears dark purplish in the living insect. Signoret says C. 
cacti is dark red-brown; those from Jamaica are better de- 
-` scribed as dark greyish. In Ency. Brit, 9th Ed. (1877), the? 
of cacti is described as dark brown. C. cacti has been intro- 
duced in Madeira, and I found it there on Opuntia in 1879. I 
have a water-color drawing made of it at the time, and it is 
represented as dark bluish-gray, not at all reddish. 
Secretion. The secretion is better described as cottony than 
mealy. As noticed by Signoret, it differs in the several races, 
