Maskell. — Oil Psyllidae in New Zealand. 159 



made out, so that an observer has no difficulty in knowing the 

 sex of the insect under examination. 



I have found no notice in pubhshed descriptions of a 

 feature which is especially noticeable in the larval and pupal 

 stages of Psyllidce ; yet I am not sure that this may not be at 

 least a character to be employed for differentiation of species. 

 I mean a distinctly-marked ring which surrounds the anal 

 orifice. This is situated close to the abdominal extreniity, and 

 the ring is of an elongated form, its edge somewhat wide and 

 having the appearance of being closely corrugated, or perhaps 

 formed of a series of small elongated pores set close together. 

 The ring seems to represent what in Coccids is termed the 

 anogenital ring. It is present in the adult, but less conspicu- 

 ously than in the larva and pupa ; and in these two earlier 

 stages it is always transverse, while in the adult (at least, 

 frequently) it is longitudinally placed above the genitalia. I 

 find that in all the species observed by me in New Zealand the 

 form of this ring varies, as shown in the accompanying figures ; 

 and I incline to the belief that it may perhaps be more use- 

 fully employed for specific differentiation, at least, than, say, 

 colour or size, or even the food-plant. 



Order HOMOPTERA. 



Family PSYLLID^ai:. 



Sub-family APHALARINiE, F. Low. 



Genus Ehinocola, Forster. 



Front of head prolonged into two conical processes ; eyes 

 prominent; forewing with a long stigma (PI. X., fig. 4, ss) ; 

 stalk of the cubitus longer than that of the subcosta ; radius 

 quite or almost straight ; genital plate of the male not pro- 

 duced posteriorly into slender processes. 



The distinctions between this and the kindi-ed genera 

 Aphalara, Forster, and Psyllopsis, Low, depend upon very 

 minute characters. In Aphalara the radial vein (fig. 4, df) 

 is usually much curved, and the genital plate of the male is 

 prolonged into two slender processes which encircle the penis 

 as in a loop. In Psyllopsis the genitalia of the male are more 

 like those of Ehinocola, but the stalk of the cubitus is only as 

 long as that of the subcosta. Ehinocola, in fact, holds an 

 intermediate position ; but it w^ould seem that some day the 

 extreme minuteness and delicacy of the characters now- relied 

 on for differentiating genera and species of Psyllidc?, must 

 bring about a simplification of the system. The progress of 

 observation in many new countries will probably make known 

 individuals combining so many features now considered im- 

 portant that the present classification cannot be kept up. 



