ZETIICfH. 29 



extremity, but without angles, delicately punctured-strigate. 



Clypeus, mandibles, and the under part of the head, yellow. 



Bess. a. diff. — This species has just the same form of head and 

 clypeus and just the same system of coloration as Z. olmecus ; 

 the petiole is also the same, but the thorax, lengthened, flattened, 

 very delieately punctured, the metathorax less excavated, with 

 not so salient carinas, make it easy to distinguish. The middle 

 carinas of metathorax stop before reaching the lateral carinae. 

 The appearance of the insect is quite different, and it looks more 

 like a Disccelius (D. zonalis) than like a Zethus ; and this 

 appearance, due to the elongate thorax, distinguishes it also from 

 Z. rniniatus and lobulatus. 



Hab. Mexico. Oriental Cordillera (Mr. Sumichrast). 



B. Antennae of Hie males terminated by a hook. 



a. Species having the appearance of the true Zethus. Head wider than high; 

 thorax short, not being one and a half times longer than wide; dilata- 

 tion of the petiole elliptical or cylindrical, a little contracted behind ; the 

 second segment of the abdomen inform of a globular bell. 



18. Z. spioipes Say. — Medius, niger, nitidus, densissime et grosse 

 cribrato-punctatus ; punctis 2 frontalibus flavis ; clypeo lato, 9 *rigro, 

 subbidentato, rugose cribrato; % punctato, albido, surpra nigro ; antennis 

 9 atris, % linea in scapo albido; abdominis secundo segmento minus 

 conspicne punctato, subpedunculato ; petiolo inflato, campanulato, grosse 

 punctato, apice ifavo-marginato. — Variat 9 % pronoto, lateribus, scti- 

 tellis, albido variegatis et abdominis secundo segmento margine albido. 



Zethus spinipes Say, Bost. Journ. I, 1837, 3S7, 9- — Sadss. Vespides, III, 

 122, 10. 



Eumenes substricta Hald. ! Proc. Acad. Pbila. II, 1844, 54. — Sauss. Ves- 

 pides, III, 152, 42. 



Zethus tari<>gatus [ Sauss. Vespides, I, 13, 9, J, 1852; Revue Zool. X. 

 1858, 66. 



Eumenes pensylvanica Hald. Proc. Acad. Phila. 1853, 365, £. 



Zethus bicolor Sauss. Vespides, I, 17, 16, £ . 



9. Insect of medium size; ocelli disposed Id a wide triangle. 

 Clypeus having the form of a transverse lozenge, twice as wide 

 as long; having the lateral extremities very sharp, and its ante- 



1 The collection, with bad locality marks, of M. dti Roman*!, has led m. 

 into very many errors. 



