ODYNERUS. 283 



From other allied species with similar livery, or adorned with 

 red, it always differs by its very sharp metathoracic ridges. (See 

 especially the 0. molestus*) 



The great number of these species all having similar livery 

 renders their distinction very difficult, so that one needs to be 

 familiar with the details of the forms, above all with those of the 

 metathorax, which furnish certain very distinctive characters. 



Hab. The United States. 2 2 taken in Tennessee. Sent by 

 E. Fr. Falconnet. 



lOl. O. Megaera Lepel. — Niger, valde pnnctatus ; metanoti foveola 

 rotundata, striata, utrinque ineruri, sed cauthis elevatis acutissimis mar- 

 ginata ; his supra in dentes 2 excurrentibus, a post-scutello per fissuram 

 sejunctis ; macula frontali et post-oculari, prouoti et abdominis segineu- 

 torum I s , 2' margine, primi utrinque aucto, macula subalari et post- 

 scutello, luteis ; alis fuseo-cyaneis. — J. Clypeo piriformi nigra, fascia 

 arcuata, vel maculis 2 luteis. — £. Clypeo lato, albido, margine trun- 

 cate, atro ; scapo fascia albida. 



Odijn. Megcera Lepel. St. Farg. Hymen. II, G36, 21 (1841).— Sadss. Et. 

 Vespid. I, 181, 74; pi. xvii, fig. 11, J 1 ; III, 232. 



<j> • Total length, 15 mm. ; wing, 12 mm. 

 % . Total length, 11 mm. ; wing, 9 mm. 



9. Clypeus pyriform, longer than wide, cribrose with coarse 

 points, terminated by a very small border, at times smooth and 

 lamellate, and appearing a little bidentate. Thorax retracted 

 on the metathorax. Head and thorax densely cribrose. Post- 

 scutel truncate, offering a subcrenulate ridge. Metathorax 

 rugose, having its lateral ridges blunted ; its posterior plate 

 concave, striate, and a little punctured on its borders ; form 

 rounded, but wider than long ; bordered with sharp ridges, but 

 not forming any lateral spiniform angles. 



These ridges a little crenulate ; their summit separated from 

 the post-scutel by a narrow fissure. Abdomen densely punctured, 

 abruptly truncate: at its base a sharp ridge; the border of the 2d 

 and the following segments very coarsely cribrose, but the border 

 of the 2d without any depressed zone. 



Insect black, clothed with a grayish pile. A spot on the 



1 The ornaments are too yellow on this figure in a -number of the 

 copies of this work. 



