FAMILIES TENTHREDINID.E AND UROCERID^. 191 



grooved piece that serves as a back to l:eep the instrument sufficiently supported : the 

 edge, upon which the teeth are cut, is circular. The use of this singular instrument is tp 

 prepare a place for the insect's eggs : slits are made in the stems and leaves of plants, into 

 which the eggs are dropped. Some of the species, after depositing their eggs, girdle the 

 branch, which consequently dies, when it forms a suitable kind of food for the young. In 

 other instances, protuberances are formed which become highly charged with sap, in 

 consequence of which the quantity of food is greatly increased. 



Cimbex ulmi (Peck), Americana ( Leach). (Plate xxvi, fig. 11.) 



The generic characters of Cimbex are : 

 Body obscurely villose : first joint of the abdomen strongly emarginate above : joints of 

 the antenna? before the club, five ; club two-jointed, and soldered together. 

 The insect I have figured is the Cimbex of authors ; but the antenna? are properly only 

 three-jointed before the club, leaving out of the number the basal support, which is fixed. 

 The first joint is the longest, and is equal to the second and third together. If the support 

 is a joint, then the antenna? are only four-jointed. 



Description (female). Head black, shining ; antenna? luteous; thorax black, margined 

 in front by a circular brownish ridge similar to a collar : abdomen bluish black with 

 brownish, marked upon the sides by four ovate yellowish white spots, and anteriorly 

 there is a whitish space between the rings similar to a belt. The substance or mem- 

 brane resembles fine parchment or paper. Wings smoke-brown, semitransparent and 

 shining ; thighs blue-black ; tibiae pale brown, and armed with blunt spurs ; tarsi 

 yellowish or pale yellow. Length |- of an inch : expanse of wing, 1| inch. 

 The body of this tenthiedo or sawfly is thick and large. According to Dr. Harris, Prof. 

 Peck had called this insect C. ulmi, because it inhabits the elm. 



The male is more slender, and the spots are wanting on the abdomen : length about one 

 inch ; breadth, two inches. The larva? feed upon the leaves of the elm. 



The foregoing species is one of the largest of the family of the Tenthredinid.s:. It does 

 not appear to be very common in the vicinity of Albany, inasmuch as but few are found 

 in our collections. 



Uroceridae. 



WOOD-WASPS : HORNTAILS. 

 The head of these insects is large, convex before and flat behind : antenna? filiform ; wings 

 long, and overlap each other upon the back' ,•■ body long and cylindrical ; rings of the 

 abdomen close and compact. Females are provided with an ovipositor in the form of a 

 slender horn projecting from the extremity of the abdomen, or from beneath it, the sheath 

 of which is attached to the inferior side of the abdomen by a hinge. In the male the horn 

 is short compared with that of the female, and is either conical or triangular. 



