354 HYMENOPTERA OF AMERICA. [PART I. 



two small triangular teeth ; scape of the antennas beneath with a 

 yellow line. 



Hess. a. diff. — A distinct, small species, well characterized by 

 its truncate, crested, black post-scutel, which distinguishes it from 

 0. coyotus, facubayse, totonacus, and by its smooth metathorax, 

 which separates it from chichimecus and iejianecus. — Comp. with 

 0. zendalus. 



Bab. The temperate parts of Mexico. Several specimens were 

 caught by me in the valley of Mextitlan, others were sent to me 

 from Orizaba by Mr. Sumichrast (5 %, 13 ?). 



15©. O. Zendalus Sauss. (Fig. 24, 24a.)— Niger, nitidus; capite et 

 thorace crasse punctatis ; abdomiue minus crasse et parum profunde 

 punctato ; scutello postice acute truncate-, cristato ; prime- abdominis seg- 

 ruento trigonali-cupiJiformi, superne tumido, prse margine constricto; 

 pronoti margine antico, scutelli fascia, abdominisque seguientorum T, 2» 

 margine, sulfureis. Alis fusco-nebulosis. — J. Clypeo rugoso; antennis 

 immaculatis. 



Odi/n. Zendalus Sauss. Revue de Zool., XXII, 1870, 140, 31. 



Total lengtb, 9 mm. ; wing, 6.5 mm. 



Form and appearance very much as in 0. Totonacus. Head 

 and thorax coarsely cribrose. Thorax wide anteriorly, narrowed 

 posteriorly. Prothorax finely crested, angulate. Post-scutel 

 strongly truncate and sharply crested; its superior face very 

 short; the posterior elevated face finely punctured; the crest 

 forming the separation of the two faces finely crenulate, its angles 

 well marked. Metathorax finely punctured, clothed with argen- 

 teous pile. Its cavity smooth, rather square. Abdomen spindle- 

 shaped; the first segment cup-shaped, subtriangular, swelled 

 above and constricted before its margin. The first three seg- 

 ments with very shallow punctures, rather large ; the following 

 finely punctured. 



Black, shining. Head quite black. Anterior margin of pro- 

 thorax, a fascia on scutel (or two spots), and the margin of the 

 first two abdominal segments, yellow. Tegulae and feet black; 

 tarsi rather ferruginous. Wings clouded with brown. 



?. Clypeus rounded, rough, scarcely emarginate ; antennae 

 quite black 



Bess. a. diff. — Quite the appearance of 0. totonacus, but very 

 distinct from this by its crested and black post-scutel, anterior 





