I02 TRANS. ST. LOUIS ACAD. SCIENCE. 



absolutely glabrous, which does not occur elsewhere in this family 

 so far as I am aware. The thorn-like extremity of the ? abdomen, 

 whence the genus takes its name, is produced by the 6th ventral 

 uniting with the 7th dorsal to form a perfectly smooth and very 

 elongate cone, the whole being jointed together so closely that it 

 requires a good lens to perceive the suture, and being basally em- 

 braced by the sides of the 6th dorsal. Occasionally from the 

 tip of this cone there projects the tip of the sheaths of the ovi- 

 positor ; but more usually they are entirely concealed within. 

 No doubt, as in Figitidce^ (see Proc, etc., ii. p. 467, fig. 3, and 

 p. 468, note,) the entire tip of the abdomen is used to pierce the 

 body of the ichneumonized insect. As will be at once perceived, 

 this is a very different arrangement from the ploughshare-shaped 

 6th ventral of Arotes and Accenitus, which, like the ventral valve 

 of Cynips, {ibid. p. 467, fig. r a,) is entirely disconnected from 

 the dorsal segments. The areolet is large and rhomboidal. The 

 bullae are very large and obvious on the brown wing, and are 3 

 in number, B, CD and E ; but as both recurrent veins are nearly 

 straight, the location of CD and E cannot be definitely fixed, fur- 

 ther than that they are always much nearer to the areolet than to 

 the other end of the vein. Out of 34 specimens carefully ex- 

 amined, the only irregularity in the bulla that I could detect was, 

 that in i <S fasciata B was obsolete, and in 3 S fasciata C andD 

 were not quite confluent. In coloration, but not in size, the genus 

 varies very considerably. 



CeratOSOma apicalis, Cress. — ^ $ . — My specimens differ as follows from 

 the description: — i. The face, clypeus and palpi are yellow Immaculate, 

 and, instead of 2 fulvous spots on the occiput, the entire occiput, except*a 

 yellow orbit narrower above and running across the entire vertex, but 

 very wide below, is ferruginous. 2. The ferruginous color of the thorax 

 is more or less densely stained with black; and there is always on the disk 

 of the mesonotum a quadrate yellow spot, the anterior angles of which 

 are connected with the clavate tip of the broad yellow line that overlies 

 the humeral suture by a more or less obvious narrow yellow vitta, thus 

 leaving an oblong blackish spot on the tip of the mesonotum. 3. There 

 is a more or less broad anterior yellow margin to the mesosternum and its 

 pleura, and a very narrow one to the pleura of the metasternum, the two 

 yellow- margins more or less entirely connected by an intermediate elon- 

 gate yellow blotch of variable size and shape, which is located at the bot- 

 tom of the pleura. 4. The terminal i of the metathorax is, as described, yel- 

 low, but on each side of its basal i there is a roundish yellow spot, which 

 is occasionally confluent with the terminal yellow part. 5. The abdomen, 



