132 HYMEN OPTERA OF AMERICA. [PART I. 



B. Metathorax not bispinose. 



a. Metathorax with rough angles. 



3. M. salvatica Sadss. — Nigra, punctata; cljpeo apice truncato; 

 uietathoracis can this rugosis baud acutis ; abdomine sessili, basi trun- 

 cato, priino segmento secundo sequilato, secuudi margine subcanaliculato 

 et valde punctato ; mandibulis, macula, frontali et post-oculari, clyp«o, 

 antennis basi, pronoto, tegulis rnaculisque 2 scutelli, ferrugiueis ; abd. 

 1° segmento repaude flavo-limbato ; pedibus ilavis, basi nigria ; alis 

 fusco-violascentibus. 9- 



Variat. Corpore plus minusve flavo-variegato. 



Monobia sylvatica Sauss. Vespides I, 93, 1 ; pi. xv, fig. 7, 9* 



Hab. Brazil. (Typus in raus. Parisiense.) 



This insect closely resembles Rhynchium (Odynerus) dor sale, 

 but it is somewhat smaller. The species seems to be distinct 

 from this, and I made some confusion with it in my Yespides III, 

 p. 168. — Compare Odyn. dorsalis, page 260, Obs. 



b. Metathorax rounded, unarmed. 



4. M. aiionaalla Sauss. 



Monobia anomala Sauss. Vespides, I, 96, 3 ; pi. xv, fig. 4 (1852). 



Hab. Brazil. (Typus in mus. Dom. Guerin Meneville.) 



Division II. 



Labial palpi composed of three articles ; the 3d carrying at its 

 extremity a 4th rudimentary article, soldered to the 3d, difficult 

 to distinguish, embodied with it, and armed with stiff hairs like 

 the extremity of the 3d. 



A. Abdomen conical; the first segment wide and truncate. 

 Hinder portion of the metathorax bordered by trenchant 

 ridges and armed on each side with a dentiform angle. 



This type establishes the transition to Odynerus from the 

 subgenus Odynerus, properly called, to Rhynchium, by its 

 quadrate thorax and its conical abdomen. 



5. M. quadridens Linn. — Valida, nigra, capite et thorace valde 

 punctatis; clypeo piriform!, apice % bidentato, 9 biangulato; abdo- 

 mine conico; pronoti maculis 2, post-seutello et abd. prinio segmento 

 supra, albidis ; % -minor, clypeo albido. 



