74 HYMENOPTERA. 



narrow, then suddenly broadening to the width of the marginal and 

 curving up to it ; the marginal vein straight, broad, broken at the 

 place where it is joined by the submarginal by a colorless area, one 

 and a half times longer than the stigmal vein, moderately long, obli- 

 quely truncate distad, the caudal angle of the truncation bearing the 

 clavate, nearly straight stigmal vein which bears the usual uncus and 

 has a very short petiole. There is no oblique line of discal cilia run- 

 ning proximo-caudad from the stigmal vein. Both sexes colored alike ; 

 lateral ocelli distant from the eye margins. Median line of mesoscu- 

 tum lighter in color ; also the postscutellum. Wings hyaline. Body 

 sculpture very slight reticulation. 



The slide bearing the 2 male and 2 female type speci- 

 mens is in excellent condition as are also the specimens 

 themselves, and besides the type number label of the U. S. 

 National Museum and a label bearing the name of the insed 

 in Dr. Howard's handvv^riting, there is also a small label bear- 

 ing the number "246°'^". 



In the National Museum collections I have also found 

 seven tagmounted specimens of this species, so labelled in 

 Dr. Howard's writing, each specimen bearing the additional 

 label "246°^ From eggs of Cicada? Issued July 29, '85." 

 All of these specimens have been remounted in balsam and 

 studied. Very little could be obtained from them otherwise. 

 They bear out the foregoing descriptive matter. 



Genus CENTROBIA Foerster. 

 1. Centrobia odonata; Ashmead. 



Centrobia odonatce Ashmead, 1900, pp. 61&-617. 



— Needham, 1903, p. 230. 



"(4) Centrobia odonatce n. sp. 



9 . — Length, 0.8 mm. Black, slender, the abdomen much acuminate, 

 ending in a prominent ovipositor. Mouth parts brownish-yellow. 

 Antennae short, 6-jointed without a ring-joint, brown-black, the flagel- 

 lum tapering oflf at apex, not ending in a distinct club. Wings hya- 

 line, the pubescence arranged in radiating rows, the margins with a 

 distinct but short cilia, the marginal and stigmal veins brown the latter 

 oblique, shorter than the marginal. Legs brownish-yellow, the femora 

 more or less obfuscated. Abdomen elongate, sessile, strongly acumi- 

 nate towards apex and more than twice longer than the thorax. 



Hab. — Lake Forest, Illinois. 



Type.— Ca.1. No. 5321, U. S. N. M. 



Host. — Odon. : Eggs of Lestes sp. Bred August 12, 1900, by Prof. 

 James G. Needham." Pp. 616-617. 



