AMEPaCAN HYMENOPTERA. 205 



tliere is no trace of a suture on the first abdominal segment. Also 

 ei/tamus Cam. It appears to be a group characteristic of California 

 and the soutlnvest ; 0. siclp/mreus Sauss. may bo taken as the type. 



a. — Lateral angles of pronotnm disihictly projecting. 



To this section belong lineativeniris Cam. and sutieranus Sauss. 

 h. — Lateral angles of pronotnm not projecting, rounded. 



To this section belong 0. cytainus Cam., 0. viselbis Cam. and 0. 

 auranus Cam., having the same coloration and arrangement of 

 abdominal black markings, but they appear to belong to Odynerus 

 s. str. As a matter of fact, it is difficult, with these insects, to find 

 a hard and fast line between Odynerus and Ancidrocerus. 



A. spilogaster Cam. merely (lifters in the yellow spot on the second 

 abdominal segment being enclosed all round. It has the projecting 

 pronotal angles of sutteranus. A. claremontensis Cam. has also the 

 spot enclosed. Pachyoder)ius cosmiogaster Cam. has, except as regards 

 the absence of the abdominal suture, the characteristic of the group. 



— ^^ Aiicistroceriis fiilvitarsitis sp. nov. 



Black ; the sides of clypeus broadly on the upper half, a small roundish mark 

 over the antennae, a short, sharply-pointed line on the base of mandibles, a short 

 line on the upper outer orbits above, a line on the base of prouotum, not extend- 

 in<;f laterally beyond the basal third, base and apex of tegulse, two large marks 

 on the scutellums, an oval mark on the pleurte below the tegulte, the apex of the 

 first abdominal segment broadly, the line dilated broadly backwards on tlie sides 

 to the top of the apical slope, the apex of the second broadly, this line dilated 

 behind into an irregular triangular incision, its outer basal half being irregularly 

 bordered with black ; the apices of the third, fourth and fifth broadly, two small 

 marks in the middle of the sixth, the second ventral segment except for a broad 

 curved irregular mark on the sides, united to a broad transverse one at tlie base, 

 the apex of this being broadly rounded and ending in a short reversed T-shaped 

 mark and a broad curved line on the apices of the others, bright sulphur-yellow, 

 except the last which is entirely black. The apices of tlie femora narrowly and 

 the tibite sulphur-yellow; the tarsi rufous-fulvous. Wings hyaline, tinged with 

 fulvous at the base, the apex with fuscous; the stigma dark testaceous. 9- 

 Total length 11 mm. 



Head, thorax and base of abdomen thickly covered with fuscous pubescence. 

 Head, prothorax and mesothorax closely, strongly punctured ; the metauotum 

 and lower part of metapleurje aciculated. Clypeus as wide as long, rounded 

 above, the narrowed apex depressed, smooth ; it is not quite transverse, having 

 a slight curve; the clypeus is somewhat strongly punctured, more or less 

 strigose towards the apex. The centre of the mesouotum is depressed in the 

 middle at the apex, the depression bordered by two longitudinal furrows. Meta- 

 notum finely obliquely striated; the ui)per, outer part bordered by a curved 

 keel, the keel continued, but not distinctly down the sides. Base of postscu- 



TKANS. AM. ENT. 80C. XXXIV. JULY, 1908. 



