SYSTEMATIC TREATMENT 69 



Morphological characteristics. Antennae 8-segmented. Two to four 

 pairs of cerarii present at the posterior end of the abdomen, the cerarian 

 spines of the anal lobe pair large and stout, of the penultimate pair some- 

 what smaller, of the third and fourth pairs more or less hairlike, usually 

 indistinguishable from the body setae. Spines of the anal cerarii sur- 

 rounded by a rather large chitinized area, containing numerous pores and 

 bearing from 8-10 rather long hairs. Remaining cerarii with few pores 

 and no hairs. Dorsum with numerous slender setae which are nearly or 

 quite as long as those on the ventral side. Many triangular pores and 

 many tubular ducts without a raised rim about the mouth. Dorsum with 

 very few multilocular pores. Anal ring large and rather weakly chit- 

 inized, the anal ring hairs slightly longer than the anal lobe hairs. 



Immature female differing from the adult chiefly in the smaller num- 

 ber of hairs and pores and the weaker development of the chitinized area 

 about the anal cerarii. 



Type host and locality. From grass at Lathrop, San Joaquin County, 

 Calif. 



Hosts and distribution. In Essig's collection from Elymus conden- 

 satus, Ventura County ; in the Stanford collection from Elymus sp., We- 

 natchee, Wash. ; Elymus sp., edge of the salt marshes at Palo Alto, Calif. ; 

 Elymus sp., at Pacific Grove, Monterey County, Calif. 



Authentication. Cotype slide examined. 



Notes : I am indebted to Mr. Ehrhorn for the loan of a cotype slide of T. 

 calif ornicus and to Mr. Essig for cotypes of Ripersia smithii. The slides labeled 

 as R. smithii contain two species, of which one will stand as Trionymus smithii 

 (Essig). The other is identical with T. calif ornicus, which is very near to, if not 

 identical with, specimens from Missouri that I have seen identified as T. ameri- 

 canus Ckll. T. calif ornicus may possibly be a synonym of the latter. 



The cotype of T. calif ornicus examined by me has two pairs of cerarii, but 

 the specimens from Elymus at Palo Alto show a tendency to the development of 

 more. In several cases they show three pairs, in some four, and in one there 

 are several cerarii on one side of the body. Otherwise these specimens are typical 

 calif ornicus, but further material may necessitate a separation. It should be noted 

 that except for the reduction in the number of cerarii this species is very similar 

 to Pseudococcus timberlakei Ckll., so much so in fact as to suggest a possibility 

 that they should not be generically separated. 



Trionymus distichlii n. sp. 

 Plate 3, fig. 28. 



In life. Occurring either upon the upper side of the leaves or at their 

 axils. Entirely covered by fluffy mass of wax. Insect of a purplish color 

 when denuded of secretion. 



Morphological characteristics. Antennae of the adult female 7-seg- 



