MESOSTENUS. 223 



middle, where there is a clearly defined area, which is longer than broad ; lower keel 

 absent ; spines stout, obtuse. The apex of the metanotum has a somewhat abrupt slope, 

 and is hollowed in the centre. Abdomen for the greater part yellowish-testaceous, the 

 underside and the sides of the petiole, a large transverse mark at the base of the post- 

 petiole, the greater part of the second segment, and of the other segments at the base (the 

 apical one narrowly), black. Petiole rather broad, the postpetiole clearly defined from 

 it, depressed in the centre at the base, the sides margined and projecting above over a 

 somewhat oblique hollow ; the sides of the petiole bearing semioblique, thick keels ; 

 the second and following segments finely and closely punctured. Legs stout, the hind 

 coxae strongly punctured ; four anterior coxae black at the base, the hind pair with a broad 

 black band down the centre on the outside, and a short one on the inner side at the 

 apex ; all the trochanters and femora lined above with black ; tarsi black at the tips, 

 covered on the lower side with stout bristle-like hair. Areolet narrow, longer than 

 broad ; the outer nervure bullated, nearly interstitial. 



24. Mesostenus corpulentus. 



Hab. Mexico, Orizaba (Bilimek). 



Very similar in coloration and punctuation to the preceding species, but larger 

 (17 millim. ; terebra 5 millim.). The head is black, there being only a short line united to 

 the oblique mark on the mesopleura along the hinder part of the mesosternal suture ; the 

 two marks on the metanotum are shorter and broader, and do not converge above ; the 

 spines on the metathorax are short, blunt, and not brought to a point at the apex, being 

 triangular, looked at from the side. The punctuation on the metathorax is stronger, 

 and runs more into reticulations at the sides and base. The femora are not clearly 

 lined with black above, and the hind coxse have a fuscous-black mark at the base, 

 not a black broad band down the centre. Wings hyaline, nervures testaceous, and the 

 areolet is wider. 



ii. Metathorax without spines. (Species 25 to 29.) 



25. Mesostenus nigrispina. 



Niger ; annulo antennarum, ore, facie, orbitis, prosterno, linea pronoti, macula mesonoti, scutello, abdominis 

 segmentis apice tarsisque posticis, albis ; pleuris, sterno, maculis 2 metanoti pedibusqne, fulvis ; alis hya- 

 linis, nervis nigris. $ . 



Long. 11 millim. ; terebra 4 millim. 



Hab. Mexico, Valladolid in Yucatan {Gaumer). 



Antennee as long as the body, slightly thickened towards the apex. Head rather 

 narrow, impunctate ; tips of the mandibles black. Thorax shining, impunctate, pleurae 

 obscurely and very finely striated. Metanotum beyond the upper transverse keel trans- 

 versely striated ; the transverse keel is straight, and there are no tubercles or spines. 



