32 



A CONTRIBUTION TO THE KNOWLEDGE OF 



but an arbitrary fashion. I have elsewhere pointed out that the genus 

 Ripersia as usually understood is a most heterogeneous group and that 

 our knowledge of the type species is insufficient to permit conclusions as 

 to its real character. I now have at hand a species (herein described as 

 Ripersia hilariae n. sp.) which is in all probability congeneric with the 

 type of this genus. If we compare this species with the types of the 

 genera Pseudococcus and Trionymus it is not at all difficult to point out 

 wherein it is generically distinct. Nevertheless it is possible to form an 

 almost complete series of species so effectually connecting these genera 

 that the points at which these groups are to be separated become entirely 

 a matter of opinion. Indeed, the series can be extended to connect in an 

 unbroken chain such diverse forms as typical Phenacoccus and typical 

 Ripersiella. 



For the present I accept the genus Ripersia as composed of forms 

 having the following characteristics : 



Pseudococcine forms in which the cerarii are apparently entirely 

 lacking or are reduced to a single pair, these on the anal lobes and with 

 the cerarian spines setiform ; with the anal ring tending to be simple and 

 at some distance from the posterior margin of the abdomen; with the 

 antennae normally six to seven-segmented. 



Ripersia hilariae n. sp. 



Fig. 14. 



Type host and locality. From a perennial grass, probably Hilaria 

 cenchroides, on the Jornada del Muerto, fifty-one miles north of Las Cru- 

 ces, N. Mex. 



Habit. Occurring beneath the sheathing bases of the leaves, sur- 

 rounded by a small amount of secretion. 



Fig. 14. Ripersia hilariae n. sp. : posterior portion of the abdomen, left half dorsal, 

 right half ventral. 



