ZETHUS. 25 



This charming insect was communicated to me by Mr. de 

 Heyden. 



** Metathorax excavated ; the excavation margined with sharp carina. 

 f Thorax short, quadrate or rounded. 



14. Z. Olmecils n. sp. — Niger, thorace crasse, metanoto crassiss-ime 

 foveolato-pnnctato ; metanoto valde excavato, acutissime cariuato ; 

 petioli tumore cylindrico, rugosissimo, carinato ; mandibulis, clypeo, 

 punctis 2 frontalibus, 2 scutelli et 2 post-scutelli, tnargineque segmen- 

 torura 1', 2', flavis ; pronoto rufo-maculato ; fenioribus posticis subde- 

 formibus. 



Total length, 11 mill. ; wing, 8 mm. 



?. Smaller than most of the preceding. Head moderate, 

 covered with scattered moderate punctures. Mandibles widened 

 to beyond the middle ; the cutting border oblique, having an 

 acute point, a rounded tooth, and an obtuse lobe. No transverse 

 carina above the antenna?. The vertex having a little arcuate 

 depression behind the ocelli. Thorax short; prothorax attenuated 

 anteriorly; its anterior border crested, the crest forming on each 

 side a little acute but not marginal angle, the anterior margin 

 being much narrower than the rest of the thorax ; the lateral 

 parts of pronotum not margined. Scutel rather salient; post- 

 scutel destitute of tubercles, quite truncate, having a posterior 

 face, punctate along its superior arcuated margin. Metathorax 

 quite angular in shape, as in some Odynerus; its whole posterior 

 face occupied by a large and deep sericeous excavation margined 

 by very sharp and prominent carina?, starting from the angles of 

 the post-scutel ; the top of the carinas separated from the post- 

 scutel by a fissure ; the inferior extremity of the posterior carina? 

 meeting the lateral sharp carina?, and forming with them a sharp 

 angle ; the upper side of metathorax divided into two triangles 

 included between the carina?. The thorax covered with very large 

 but not deep punctures; still larger on the metanotum, where they 

 are nearly little grooves. Petiole having its swelling cylindrical, 

 extremely coarsely punctured, the punctures very large and con- 

 fluent; the middle somewhat carinated by the rough sculpture, 

 the extremity a little contracted and with a large groove • on 

 each side in the middle an obsolete sort of a tooth ; the anterior 

 extremity of the swelling truncate, polished. Second segment 

 subsessile, convex beneath at base, but not tuberculous; tenuously 



