378 U.S. NATIONAL MUSEUM BULLETIN 236 



men proved to be completely successful and shows several points of 

 difference with Cletopsyllus Willey, 1935, with which it is undoubtedly 

 closely related. 



The body, in P. spiniger, is heavUy armed with spines; in C. 

 papillifer there are no such spines. 



Leg 1, in P. spiniger, has no internal seta on the 2nd exopodal 

 segment; such a seta is present in C. papiUifer. 



Leg 3 has the same setal formula in both species, but in Willey's 

 drawing of this appendage (Willey, 1935, fig. 81), he figures 3 internal 

 setae at the 3rd exopodal segment (only 2 according to the setal 

 formula). 



Leg 4, in P. spiniger, has 2 internal setae on the 3rd exopodal 

 segment, bringing the total number of appendages on this segment up 

 to 7; 3 are present in C. papillifer, with a total of 8. 



There are many differences in shape and setation of leg 5, as a com- 

 parison on the drawings of both appendages will show. Noteworthy 

 is the long baso-endopodite in P. spiniger and its fusion with the 

 exopodite. 



The combination of characters mentioned above prompted me to 

 place the specimen to be described below in a new genus, the more so 

 since the setation of the legs is of fundamental importance in the 

 characterization and the limitation of genera in the Laophontidae. 

 In this connection special importance must be attached to the absence 

 of an internal seta on the 2nd exopodal segment of leg 1 although it 

 must be admitted that the corresponding seta in Cletopsyllus is very 

 small and fine. 



Pseudocletopsylliis spiniger, new species 



Figures 148, 149 



Material. — Loc. 594, 1 ad. 9, 0.66 mm. 



Description. — The following is based on the above-mentioned 

 holotype specimen ; it has been dissected and mounted. 



Adult female, total length 0.66 mm.; gi-eatest diameter 0.18 mm.; 

 f ureal setae broken. 



Body strongly built, of very characteristic appearance, slightly 

 depressed dorsoventrally, greatest diameter at 3rd thoracic somite 

 and very gradually narrowing posteriorly (fig.l48i). Head and 1st 

 thoracic somite fused; cephalic somite occupies, with rostrum, % 

 length of body. Cephalic somite dUated in oral region, extreme 

 posterolateral corner laterally produced and pointed. Distinct 

 groove runs backward from insertion of antennules. Rostrum big 

 and heavy, inserting with broad base, reaching halfway along 2nd 

 antennular segment, slightly curved downward. Apex rounded, 

 minutely bifid at tip, with two fine hairs. Thoracic somites 2 to 5 of 



