•94 FIFTH ANNUAL REPORT 



It will be seen that in thus distinguishing these three species, M. 

 Signoret attaches a great deal of importance to the number of anal 

 secretors. Judged by this criterion, our own insect, under considera- 

 tion, can not be referred to either species, and is consequently unde- 

 •scribed. The name being appropriate, it would have pleased me to 

 refer it to Bouch6's pomorwn^ and in the secretors it comes nearer to 

 that than to the other species; but aside from the difference in the 

 secretors, the difference in the color of the eggs is an insuperable 

 objection, as I find this character the most constant. Noticing that 

 in his generic diagnosis M. Signoret says that the eggs of Mytilaspis 

 are always either white, yellowish or grayish, and knowing that those 

 of our species, though normally pure white, become discolored and 

 ferruginous when addled or otherwise injured, and are always yellow- 

 ish just before hatching, it struck me that this author might have 

 made a mistake in describing those oi jyomorum as " deep red." And, 

 in fact, after examination of specimens of our insect received from 

 me in 1870, he was inclined to think the two identical, and that he had 

 made a mistake. But there is Bouchers original description, in which 

 the eggs are distinctly described as red brown, and which effectually 

 separates the two forms ; and as <ion<ihiformis is properly relegated by 

 Signoret to the species on the Elm, and may be considered distinct, 

 not only on account of the differences indicated above, but of the 

 negative evidence that our apple-tree species does not affect the Elm, 

 there seems no other course left but to give our insect a new name. 

 I have little doubt that the species occurring on the Apple in England, 

 and treated of by "Ruricola" (Jno. Curtis) in the Gardeners^ Chron- 

 icle^ 1843, p. 736, under the common name of "Apple-tree Mussel-scale 

 or Dry scale," and the scientific name of Aspidiotus GoncJiiformis, is 

 the same as our poinioorticis^ for though the mother louse is de- 

 scribed as "fleshy-green" and "yellow-green," the eggs are said to 

 be white, and the size, form and habit otherwise coincide. The same 

 may be said of the European apple tree species mentioned by Bois- 

 ■duval and by Taschenberg, who describe the eggs as white. 



Now, these four bark-lice certainly bear sufficient resemblances 

 to be mistaken lor one species; and whether they really constitute 

 but one species, merely varieties of one species, or four genuine 

 species, according to the usual acceptation of the terra, can only be 

 definitely ascertained when the males of all are known, and when, by 

 experiment, it is found that the one can not live upon the food-plants 

 of the other. A slight difference in the number of anal secretors can 

 not be looked upon as of sufficient specific importance when all other 

 characters agree; for the number, as we have already seen, is not 

 constant. Yet, there is no doubt a limit to the variation from the 

 ordinary number, and the differences noted above probably have their 

 value, and at all events are made by the highest authority. It will 

 •certainly facilitate our study to have these four insects separated, and 



