1838.] 1 25 



Thus "aceris has the 2nd and 3rd joints of the antennae the longest, and the 

 others diminishing in bulk and length ; cesculi the 2nd and 3rd joint the longest, 

 the others diminishing up to the last, which is as long as the two preceding ;" 

 mespili " the 2nd joint the largest, the 3rd nearly equal, the others diminishing up 

 to the 9lh, which is twice as long as the preceding one ;" platani "the 2nd joint 

 the longest, the others diminishing progressively up to the 9th, which is half as long 

 as the preceding one, the 6th, 7th, and 8th smallest like the 4th, which we also see 

 in aceris, whilst in cesculi the 4th is nearly equal to the 5th." Of brunitarsis it is 

 said that " the 2nd and 3rd are the longest, the 1st twice as thick, the 9th a little 

 longer than 3rd, nearly equal to the preceding two together;" the length of the 

 body of this species is only 1-5 mm. Of hederce it is said that " the 3rd and 9th 

 joints are the longest, then the 2nd, 4th and 5th, the 6th, 7th and 8th the smallest 

 and equal, the 9th one and a half times longer than the 8th." 



Ps. ulmi in general appearance, and in the want of tarsal digitules, 

 is like Ps. ulicis (p. 88 ante) ; but that is a much smaller insect, and 

 although, as in that species, the 5th joint of the antennsB is longer 

 than the 4th, yet it has not the same proportion, for in the present 

 species the 4th is not so remarkably short ; the 9th joint is also much 

 longer ; other differences in the form and character of the marginal 

 projections of the body, the ultimate covering, &c, are also apparent. 



The species of Pseudococcus are slightly yet distinctly differen- 

 tiated, indicating their descent from a common stock. Except aceris, 

 each appears to be restricted to one food-plant. 



Towards the end of May, 1886, on an elm bush {Ulmus campestris) 

 at Brockley, which I have not been able to visit since at that season, 

 I found five adult ? female examples of this insect, of which one on 

 the next day enveloped itself with a close-fitting, felt-like covering, 

 measuring 5 mm. in length ; the others were at once killed and served 

 for the foregoing description. 



I am indebted to Mr. E. T. Lewis for the excellent camera draw- 

 ings here reproduced. 



8, Beaufort Gardens, Lewisham : 

 September, 1888. 



* In the " Table ge"n£rale des Especes," p. 498, of Signoret's " Essai sur les Cochenilles,' 

 Pseudococcus aceris, as described at p. 363, is attributed, as a species, to Geoffroy, but this is a 

 lapsus calami, for Signoret himself, in his "Catalogue des Coccides," at p. 39, cites Geoffroy's 

 aceris as an Aleurodes ; and in his previous " Essai monographique sur les Aleurodes" (Ann. Soc. 

 Ent. de France, 4 Ser., Tom. viii, p. 394, 1868, he described the Chermes aceris ovatus of Geoffroy 

 as Aleurodes aceris, citing Baerensprung (Alton and Burmeister's " Zeitung fur Zoologie," p. 176), 

 who said that without doubt Geoffroy had described the larva of an Aleurodes under that designa- 

 tion. The name, therefore, is Ps. aceris, Sign., nee Geoff. This should be noted, as Prof. Comstock 

 (Report for 1880, p. 345), in describing Ps. aceris as a native of N. America, follows Signoret in 

 attributing the specific name to Geoffroy. 



The dimensions of Ps. aceris, ?, are given (I. c.) as "d'une longueur de 4 — 5 mm. sur 8 de 

 large ;" the latter figure is an obvious typographical error, and it should probably be read as "3." 



