108 PROC. ENT. SOC. WASH., VOL. 20, NO. 5, MAY, 1918 



stead of convex. No investigation of the internal structure of the 

 head was made. It is of interest to note that drones of this sort 

 are said to have appeared in some numbers in a hive together with 

 other drones having eyes of the normal size and form, but deficient 

 in pigment. This condition is apparently paralleled by that found 

 in the fruit fly, Drosophila, in which individuals having the eyes 

 either entirely or partially lacking appeared and were bred in con- 

 siderable numbers. 3 This character, "eyeless," proved to be 

 inherited according to Mendelian principles. Hoge 4 found that 

 flies having the eyeless character either lacked eye pigment and 

 ommatidia or had one or both eyes reduced in size, and that 

 such flies were also less viable than the wild stock. It is suffi- 

 ciently obvious that this character would not be likely to. gain much 

 headway in the honeybee owing to the fact that deficiency in 

 vision in the drone would doubtless hinder mating, if not altogether 

 prevent it. 



THE GENUS PLINTHISUS LATR. [LYGAEIDAE-HEMIPTERA] IN 



THE UNITED STATES. 



BY H. G. BARBER, 

 Roselle Park, N, J. 



This genus can be differentiated from all of the other United 

 States genera of the Tribe Rhyparochromini of the Lygaeidae by 

 the third ventral suture of the abdomen being straight laterally 

 and reaching the margins on each side. Other reliable characters 

 are as follows: the head narrower than the pronotum anteriorly 

 which is cut out or concave in front, to receive the head which is 

 commonly sunk to the eyes (P. compactus Uhl. is an exception to 

 this) ; lateral edge of the pronotum more or less strongly keeled, the 

 anterior lobe, except in front, impunctate; scutellum large, com- 

 monly somewhat equilateral or broader than long; clavus not 

 deflected to the corium but flat; membrane commonly abbreviated 

 or absent; first segment of antennae well extended beyond apex 

 femora much swollen and most commonly armed with two or more 

 teeth; fore tibia of male more or less curved and expanded apically ; 

 shining, color ferrugineus, castaneus or ochraceous. 



Lethierry and Severin list 29 species of Plinthisus as occurring 

 in the Palaearctic Region. P. compactus Uhler 1904. from New 



'Morgan, T. H., Sturtevant, A. H., Muller, H. J., Bridges, C. B. The 

 Mechanism of Mendelian Heredity, p. 14. New York. 1915. 



4 Hoge, Mildred A. Another gene in the fourth chromosome of Droso- 

 phila. Amer. Nat. XLIX, 57.7, pp. 47-49. 



