46 THE ENTOMOLOGIST. 



suppose that we ought not to look upon the tubercles of, say, 

 Eriococcus and Dactylopius as morphologically distinct at all. In 

 both cases they seem to be only processes visible at each side of 

 the abdominal extremity, and they always bear a more or less 

 numerous arrangement of hairs and spines. Carrying this view 

 a little further, we might say that they correspond sufficiently 

 with the abdominal lobes of the Lecanids. But, when we come 

 to attempt a clear and convenient classification, we find that the 

 forms {AcantJiococcidce) possessing antennge with short terminal 

 joints and anal rings with eight hairs, exhibit almost always 

 tubercles differing considerably from those of the forms {Dacti/lo- 

 pidce) with long terminal joints and anal rings with six hairs. 

 Some of the AcantJiococcicUe, e.g., Rhizococcus casuaritK^, Mask., 

 or Eriococcus tiLr(jij)es, Mask., have comparatively small tubercles; 

 Bonie Dactylopiihe, e.g., Dactylopius nipce, Mask., or Riper si a fa cji. 

 Mask., have comparatively large ones. Yet there is a very long 

 way between them, and there is no mistaking their character. 



The form of the tubercles in a Dactylopid is usually rounder 

 and less cylindrical than in an Acanthococcid ; the spines and 

 setae, where they occur, are more scattered ; and the margins are 

 much less irregular. As a rule also they appear to be less 

 ehitinous. After treatment with potash, it will usually be found 

 that the feet, antennae and rostrum of a specimen remain of a 

 much darker colour, with more solid appearance, than the rest 

 of the body ; so also do the abdominal lobes of a Lecanid, or the 

 anal tubercles of an Acanthococcid. But the tubercles of a 

 Dactylopid seem generally to be less hard. There are exceptions, 

 as in Ripersia fagi, where the tubercles remain slightly darker, 

 but these are few. Even in Eriococcus tunjipcs the tubercles, 

 though small, are conspicuously dark and hard. 



Some Daciylopidoe have the tubercles reduced nearly to a 

 mere dot ; in others they seem altogether obsolete : examples 

 may be seen in Dactylopius adonidum, D. calceolaria, Ripersia 

 tomlinii, Pseudococcus astelice, &c. And I do not doubt that 

 somebody will arise, some day, fastidious enough to separate 

 under new subgenera the species with very minute from those 

 with more noticeable tubercles. The time for this hair-splitting 

 -does not seem to me to have yet arrived. 



The tubercles of D. nipa are fairly large for the genus, and 

 they approach those of some Rijyersice ; and it was jiartly on this 

 account (in addition to the cottony processes) that in 1892 I 

 stated that it might almost be a Ripersia if other characters did 

 not forbid it. I cannot detect any Acanthococcid feature in it. 

 In the next volume of our ' Transactions ' I propose to give 

 some figures illustrating the differences in the anal tubercles 

 which have just been mentioned. 



Wellington, New Zealand, Oct. 12, 1893. 



(To be continued.) 



