346 BULLETIN LTJITED STATES GEOLOGICAL SUEVEY. [YolY. 



Stizus Latr. (1802). 



Syn. Larra Sm. (nee Latr.)- 



Bicyrtes Lepel. 

 Type: Stisus tridentatus {Crahro tridentatus Faibr., Stizus iifasciatus Jjatr.). 



Eighth ventral segment of the male triclentate ; i. e., armed with three 

 spines. Male antennae unarmed ; the apical joint excavated beneath, 

 not elongate. Labrum with the length two-thirds of the breadth. Sub- 

 medial cell of the posterior wings narrow, extending much more than 

 its own breadth beyond the origin of the transverse medial nervure. — 

 Head transversely flattened posteriorly, the cheeks behind the eyes be- 

 ing obsolete or in a plane with the occiput. Eyes distant on the vertex, 

 converging beneath, the inner margin very slightly excavated above. 

 Clypeus subquadrate, the breadth a little greater in the female, the 

 length in the male ; the sides somewhat rounded, both the upper and 

 lower margins excavated. A slight carina between the antennse. 

 Mandibles slender, pointed, entirely unarmed in either sex. Apical 

 joints of the male antennae pitted beneath. Legs slender, the pulvillus 

 small. Anterior tarsi of the female slightly dilated, the basal joints 

 produced at the tip externally ; ciliate externally with spines, wliich 

 equal the fifth joint in length. Dorsal valve of the female without 

 enclosure, pointed; dorsal valve of the male shorter and obtuse, depressed 

 and not large. Eighth ventral segment of the male with only the tips 

 of the spines prominent; claspers small and slender. 



Smith (C. H. B. M. iv, 337, 185G) quotes Stizus from Latreille's Gen. 

 Crust, et Ins. iv (1804), and states that Stizus Hogardii was Latreille's 

 type, but erroneously, for it was in 1802 that LatreiUe, in his Hist. 

 Nat. vol. iii, established the genus Stizus, and gave bifasciatus and 

 ruficornis as species under it, without mentioning Hogardii. In 1805, 

 Hist. 'EaAi. vol. xiii, Latreille added tridens to the genus. 



Klug, in the Symbolse Physicae, Insecta, vol. v (1829), without defining 

 the genus, treats of species of Stizus under the generic name Larra, 

 erroneously quoting Fabricius as the authority for the latter genus. 



Smith also gives Larra vespiformis as the type of this genus ; but that 

 species is not mentioned by Latreille, and if it should prove to be gen- 

 erically distinct from Mfasciatus would belong to a 'new genus. Stizus 

 unicinctus Say is the American representative of Mfasciatus. Some of 

 the species here catalogued will require to be placed in distinct genera. 



1. Stizus TJ]snciNCTus. 



Stizus unicinctus Say, West, Quart. Eep. ii, 77 (1823) ; Am. Ent. 4, pi. 2, f. 3 and 



4, $ (1824). 

 Larra unicincta Cress., Proc. Ent. Soc. Phila. iv, 472 (1855). 

 Larra unicincta Pack., Proc. Eut. Soc. Phila. vi, 444, $ $ (1867). 



Habitat : Kansas, Colorado, Utah, Wew Mexico, Texas. 



2. Stizus seevillii. 



^icyrfes jSerwHti LepeL, Hym. iii, 53, 9 (1845). 

 Larra Servillii Smith, C. H. B. M, iv, 350 (1856). 



Habitat: Philadelphia. 



