616 PROCEEDINGS OF THE NATIONAL MUSEUIM vol. xn 



genus the specimens under consideration also appear at the end of the 

 key after all the more readily recognized species have been separated. 

 Thus, a point of relatively little differentiation is reached and further 

 separation becomes very difficult. 



Perhaps this melange could be treated as a "Rassenkreis"; however, 

 the nature and geogi-aphic distribution of the variation exhibited 

 by the specimens studied does not conform to that required by the 

 accepted definition of a polytypic species. In view of these considera- 

 tions the most practical arrangement is to treat these specimens as 

 one species, unless and until investigation of additional characters 

 in the phallosome and the internal female genitalia reveal means for 

 their separation into additional species. Until this is accomplished, 

 St^l's name lugubris has priority over the other names that have 

 been applied to specimens belonging to this complex. 



Dallasiellus (Dallasiellus) murinus (Van Duzee), new combination 



Plate figure 277 

 Geotomus murinus Van Duzee, 1933, p. 26. 



Diagnosis. — Among those species that are less than 6 mm, in length 

 and have three widely separated setigerous punctures on the 

 submargin of the head, this species may be detected by the single 

 setigerous puncture on the costa, the polished mesocorium and the 

 longitudinal impression on each jugum. 



Description. — From four males and four females. Male: Elon- 

 gate-oval, sides subparallel. 



Head: Length about two-thirds width, 0.86(0.80-0.91): 1.26(1.22- 

 1.32); interocular width, 0.77(0.76-0.80); anterior outline semJ- 

 circular, clypeus as long as jugum, strongly narrowed apically ; surface 

 shining, with numerous, well scattered, minute punctures; jugum with 

 longitudinal, obtuse impression medially, this marked laterally by 

 longitudinal tumid elevation anterior to eye, with three widely 

 separated setigerous punctures submarginally ; ocelli small, separated 

 from eye by space equal to or IK times transverse ocellar width ; jugum 

 ventrally and maxillary plate (except basally) shining, impunctate. 

 Antennal segments: I, 0.28(0.26-0.30); 11, 0.32(0.30-0.36); III, 

 0.35(0.33-0.36); IV, 0.45(0.42-0.49); V, 0.50(0.47-0.54), Bucculae 

 about as high as labial II, evanescent posteriorly; labium reaching 

 between middle coxae. Labial segments: I, 0.44(0.43-0.46); II, 

 0.81(0.69-0.73); III, 0.54(0.50-0.60); IV, 0.31(0.29-0.36). 



Pronotum: Length slightly more than half width, 1.31(1.23- 

 1.38) : 2. 55 (2.47-2. 60) ; anterior margin moderately doubly emarginate; 

 lateral margin entire, straight on basal half, with six setigerous 

 punctures submarginally; transverse impression postmedian, dis- 



