35 
about seven on an average, perhaps. These orifices are considerably larger than in 
confusus. Antennae as usual in the genus. Legs much larger than in confusus ; femur 
stout. Truncate spines very narrow (in the Jamaican insect they are very broad), 
with some complete spines among them. The insect, flattened under a cover glass, 
is 5 mm. long and 3 broad. 
(2) The Jamaican insect. Secretion profuse, as in confusus. Truncate spines 
thick, as in tomentosus. I am inclined to suppose that this may be the variety called 
"syl restrc," but as I have seen no clear description of that form I am in doubt. 
(3) C. tomentosus. Found in the Guanajuato region of Mexico. The females are 
not imbedded in profuse secretion as in confusus, but are clearly separable, being 
nevertheless each one enveloped in secretion, and not almost naked as in typical 
cacti. This was supposed to be the " sylvestre" = tomento»u» } by Lichtenstein. who 
had previously placed it (in MS.) as a new Acanthococeus. It appears that he noticed 
tin' insect; under the name tomentosus, in Bull. Soc. Ent. France, 1884. 
Dr. Duges kindly lent me a letter which Lichtenstein wrote him on 
July 4, 1S84, containing the following passage, freely translated: 
"I suppose you note that I have not published the Opuntia coccid 
under the name Acanthococeus opuntim, for I have found that Lamarck 
had named 'la Cochenille sylvestre du Mexique' Coccus tomentosus. I 
must use the specific name, though 1 am not sure that it is the same 
insect, not yet having been able to consult Lamarck's work in that of 
Thierry de Merouville. I will do this in the winter." 
I would not here publish Lichtensteiu's original manuscript name did 
I not think that it would have to be brought into use, owing to the uncer- 
tainty about tomentosus. In such case we can call the Guanajuato form 
C. cacti subsp. opuntice (Liclit. MS.). 
(4) C. confusus. Antenna' 7-joiuted in well-developed individuals; joint 4 decid- 
edly longer than in Signoret's iigure of cacti. Smaller than cacti, and enveloped in 
profuse secretion, so that I presume it would be impossible to use it commercially. 
This is the form inhabiting the southwestern United States. The 
most northern locality from which I have seen specimens is Colorado 
Springs, Colo., November, 1894: (Professor Gillette). Professor Tourney 
sends it from Tucson, Ariz., on Opuntia versicolor Engelm. 
Still another form, the G. bassi Targ., is quite unknown to me. In 
Ceylon, also, where the species has been introduced, Mr. E. E. Green 
recognizes not only the typical form, but a variety which he has named 
ceyloidcus. 
Note. — Mr. Clarence E. Rhodes, one of my students in zoology, has been working 
out the relative amounts of pigment, weight for weight of the insects as gathered, 
in the different forms of Coccus. Following a method suggested by Professor Goss, 
chemist of the New Mexico Agricultural Experiment Station, it was ascertained that 
taking commercial C. cacti as 100 the pigment in the same weight of tomentosus 
(ojHintia') from Guanajuato was equivalent to 80, while that of C. confusus from Las 
Cruccs was equivalent to only 10. It is evident that confusus is of practically no 
commercial value. 
