128 BULLETIN 66, UNITED STATES NATIONAL MUSEUM. 



Prothorax: Length =10; breadth = 28. 



Mesothorax: Length = 10 ; least breadth = 24 ; greatest breadth = 39. 



Balancer, or elytron: Length = 34. 



Metathorax: Length = 110.5; prasscutum plus scutellum = 54; post- 

 lumbium = 13; postscutellum = 43.5; greatest breadth = 47. 



Abdomen: Length tenth segment = 18; length csdeagus = 20. 



Anterior leg: Trochanter = 29; femur = 35; tibia = 36; tarsus = 29. 



Median leg: Trochanter = 25; femur = 35; tibia = 34; tarsus = 29. 



Posterior leg : Trochanter =14; femur = 38 ; tibia = 30 ; tarsus = 29. 



In addition to these measurements actual measurements by a 

 cruder method were taken, as follows: 



Length of body = 3.3 mm. 



Length of head and thorax = 2.1 mm. 



Breadth of head = 0.8 mm. 



Length of wing on costal margin = 1 .9 mm : on anal margin = 2.2 mm. 



Type.— Cat. No. 10114, U.S.X.M. 



5. ACROSCHISMUS PECOSENSIS, new species. 

 Xenos nigrescens, determinations in collection of Anirr. Ent. Soe. Philadelphia. 



Host. — Polistes texanus Cresson: Pecos, Texas, February 27, 

 September 30; Austin, Texas; Victoria, Texas. Polistes rubiginosus 

 Lepeletier: Waco, Texas, August 29; F.'C. Bishopp, collector (pi. 7, 

 figs. 3, 7, 12; pi. 8, figs. 1, 4; pi. 9, fig. 7). 



Male. — Length, 3.8 mm. Color, brown; antennas, light brown; 

 mandibles brown at base, yellow at tip; eyes black; wings with costal 

 margin brown ; legs lighter, yellowish ; oedeagus clear yellow. Antennas 

 as long as breadth of head, very sensitive, pubescent, first joint con- 

 cave for reception of second. Maxillae yellowish, pubescent, nar- 

 rowed to one-half original diameter beyond middle, apically rounded; 

 palpus arising at the apical one-third and somewhat surpassing the 

 apical lobe of the maxilla. Mandibles ensiform, over twice the 

 length of the maxillae. Mesostigmatal lobe present. (Edeagus 

 reflexed, angled at thickest point above, apex turned at an obtuse 

 angle above. It differs from that of A. pallidus in that the latter is 

 rounded at the thickest point, and has the apex turned at an acute 

 angle above. 



The following accurate measurements were taken on the same scale 

 as in A. pallidus texensis, one space = 0.0157 mm. 



Antennas: Length = 67; fourth segment = 60; greatest breadth = 7. 



Head: Distance between outer basal corners of antennas = 25; 

 between inner front edges of eyes = 32 ; between inner hind edges of 

 eyes =46; breadth of head = 65. 



Mouth parts: Mandibles =26; maxilla = 12; distance to base of 

 palpus or second joint =8; palpus =4. 



Prothorax : Length = 12; breadth = 30. 



