THE COCCIDAE OF SOUTHWESTERN UNITED STATES 57 



Female. Adult female oval in form, the anterior end rounded, the 

 pygidium slightly pointed; cephalothorax more or less heavily chitinized, 

 not wider than the abdomen at its base. Pygidium with the median 

 lobes well developed, rather square, with a notch on the lateral margin. 

 Second pair of lobes present but very small, bilobed. Third pair of 

 lobes obsolete. Between the first and second lobes is a low gland promi- 

 nence and between the second and the position of the third a prominent 

 plate or gland spine. A small spine is situated at the inner basal angle 

 of each median lobe. A rather large spine marks the position of both 

 the second and third lobes, the thickenings about the sockets of these 

 spines being quite conspicuous. Dorsal tubular ducts few, slightly 

 smaller than the marginal ducts ; their arrangement is indicated in the 

 figure. Anal opening at some distance from the margin. On the ventral 

 side the spines are extremely small. Vaginal orifice small, set in a de- 

 pressed area. 



Notes : The specimens from Yucca differ from the others in having the 

 second exuvium brown instead of black and in a tendency toward a much lighter 

 chitinization of the cephalothorax of the adult female. Otherwise they are in all 

 respects like the typical form. 



Genus XEROPHILASPIS Ckll. 



As far as I am able to determine this genus has never actually been 

 defined. I present the following characterization of it : 



Diaspine Coccidae in which the adult female is entirely enclosed by 

 the exuvium of the second stage; adult female without circumgenital 

 pores, without plates and with the lobes reduced to slight prominences : 

 immature female with three pairs of well defined lobes and with large 

 tubular ducts of the type found in Diaspis and related genera. 



Type of the genus X. prosopidis Ckll. 



Notes: As the genus Aonidia is at present understood X. prosopidis might 

 well be considered as belonging to that genus. However, there can be but little 

 question that the genus Aonidia in reality includes forms of very diverse phylogeny 

 and that the retention of the adult female within the derm of the preceding stage 

 is a character that has developed independently in totally unrelated groups. In 

 fact a classification based upon the second stage would in all probability come 

 much closer to expressing the real relationships of these curious forms than does 

 that now in use. I therefore retain the genus Xerophilaspis rather than add one 

 more to an already heterogeneous assemblage. 



The real nature of X. prosopidis appears not to have been understood, for 

 the exuvium of the second stage seems to have been confused with the secretionary 

 scale and the differences between this stage and the adult have not been noticed. 



