2l6 P. CAMERON. HYMENOPTERA. 



Mesostenus belong apparently M. multipictus Smith, Journ. Linn. Soc. VII, p. 8; Tosquinet, 

 Mem. Soc. Ent. de Belgique, 1903, 152; erroneus Tosq., Le. 135; piideus Tosq., Le. 164. 



To Mesostenoideus belong leucozonus, Brullé, Hymen., IV, 231, from Dorey; it has, for a 

 Mesostenus or Mesostenoideus a very long ovipositor, 35 m. m., with a body length of iom.m. ; 

 arrogans, Smith, Journ. Linn. Soc, VIII, 63 ; pulcherrimus, Smith, /. c, VII, 8 ; this has a 

 white spot on the mesonotum and cornes near M. ornatifrons described in this paper, but 

 differs in having the head spotted wtth white; anthracinus, Tosq., /. c. 123, austerus, Tosq., 

 Le. 129; disgregus, Tosq., Le. 129; enitescens, Tosq., Le. 131 ; palatus, Tosq., Le. 158; 

 sinudator, Tosq. Le. 165. 



Mesostenus, Gr. 



The species of Mesostenus, sensu str., described hère may be separated thus : 



1 (2) The mesonotum with a conical mark, the marks on vertex united in front ornatifrons. 



2 (1) Mesonotum immaculate, the marks on vertex separated. 



3 (10) Base of abdominal pétiole yellow. 



4 (7) Apex of metanotum bimaculate. 



5 (6) Hind coxae entirely black below, the hind femora at the sides and below fulvous, the 



mark on mesopleurae small, square; metanotal marks not extending much above the 

 top of the apical slope, the abdomen normal in size and width . . leucostoma. 



6 (5) Hind coxae not entirely black below, the hind femora below pallid yellow, the mark on 



mesopleurae large, longitudinally oval; the abdomen long and slender; the metanotal 

 marks projecting clearly above the top of apical slope .... graciliventris. 



7 (4) Metanotum unimaculate. 



8 (9) Metanotal mark not dilated on either side at the apex, the hind femora black. Tosquineti. 



9 (S) Metanotal mark dilated laterally at the apex, the hind femora red . . pulchripes 

 10 (3) Abdominal pétiole black at the base, the mark on metanotum large, triangularly incised 



in the middle at the base and apex ....... basiornatus. 



1. Mesostenus pidcliripes sp. n. 



Bivak Island, February. 



Black, palpi, a mark between the eyes and the ocelli, touching both, its top rounded, 

 the apex narrower and more oblique, the 9* to 17* antennal joints, tegulae, scutellums, a 

 mark on the metanotum between the keel and the apex, the basai two-thirds hardly one third 

 of the width, the apical third gradually expanding to the outer apical edge, a curved mark 

 behind the wings, reaching slightly below the keel, and more narrowed there than on the 

 top, a mark on the upper apical half of the metanotum, touching the metapleurae, straight 

 on the inner side, rounded and narrowed in the middle on the outer, the ist abdominal segment, 

 except for a black mark, a little longer than wide, trilobate at the base, the apex transverse, 

 a band, less than one fourth of the 2nd segment, prolonged laterally to the gastracoela, its 

 apex irregular, its apical fourth and similar, but narrower bands on the apices of the others, 

 the bands becoming gradually narrower, the centre of the 1 st ventral, the base and apex of 

 the 2 nd and the apices of the others, pale yellow. Génital armature black. Four front legs 

 white, a fuscous line on the top of the femora, and the tibiae and tarsi fuscous, the former 

 lighter in tint, the tibiae with a white band near the base, the hind coxae and trochanters 

 black, the former white above, the femora red, narrowly black at the apex, the tibiae white, 

 the base narrowly, and the apical fourth black, the tarsi white, the apices of the basai 3 joints 



