HYMENOPTERA. 587 



Ichneumon proper, has the head transverse, the abdomen oval, nearly equally narrowed at each end. [Numerous 

 British species.] Panzer has separated, under the name of Trogus, those species which have the scutellum in the 

 form of a conical tubercle, and the abdomen marked by deep transverse impressions. 



Alomyia, Panzer, has the head narrower and more rounded, with the abdomen more dilated towards the poste- 

 rior extremity. 



Hypsicera, Latr. [Tryphon (Exochus) Grav.], has the appearance of Alomyia, but is remarkable for its pyramidal 

 head, with a frontal elevation supportina; the antennje. 



Peltastes, lllig. (Metopius, Panzer), has the abdomen united to the thorax by the greater part of its transverse 

 diameter, subsessile, and slightly dilated towards the extremity. Ichn. necatorius, Panz. [and two or three allied 

 British species]. They have a circular elevation beneath the antennae. 



The second and last division of the species with 5-jointed maxillary and 3-jointed labial palpi has the labium 

 deeply notched, and the ovipositor is exserted and covered at the base by a vomeriform plate ; the hind thio-hs 

 are thick. 



Acanitus, Latr., has the front of the head not produced into a beak. In 



Agathis, Latr., it forms a beak. These insects approach in their wings the following subgenera. 



Our second division of the Ichneumons differs from the preceding in respect to the joints of the 

 palpi only, in consequence of the labial palpi having only three joints, as in the majority of the species 

 of the following division ; the second cubital cell is nearly as large as the first, and nearly square ; the 

 ovipositor is exserted ; the tip of the mandibles is bifid or notched. 



Bracon, Jur., has an evident hiatus between the mandibles and clypeus ; the maxillse are prolonged inferiorly 

 beneath the mandibles; the second cubital cell is square and rather large ; the ovipositor is long; the antenna; 

 are setaceous, as long as the body, and the maxillary palpi are much longer than the labial. 



Vipio, Latr., has the antennze shorter and filiform ; the maxills are proportionably larger, and form a kind of 

 beak, and the maxillary palpi are not much longer than the labial. 



Microgasfer, Latr., does not exhibit any decided hiatus between the mandibles and clypeus ; the maxillae and 

 lower lip are not prolonged ; the second cubital cell is small. The ovipositor as well as the abdomen is short. 



Our third and last division, corresponding with the genus Bassus of M. Esenbeck, has like the 

 preceding, four joints in the labial palpi, but the maxOlary palpi are 6-jointed; the abdomen is 

 semi-sessile. 



In some the mandibles are gradually narrowed to the tip, and terminated by two teeth. 



Helcon, Nees, has the abdomen, seen from above, composed of several joints, and terminated by a long ovi- 

 positor. 



Sigalphus, Latr., has the abdomen vaulted beneath, and only 3-jointed above, with the ovipositor withdrawn and 

 sting-like. 



Chelonus, Jur., has the abdomen similarly formed beneath, but inarticulated on its upper suface. 



Alysia, Latr., has the mandibles nearly square, with three teeth at the tip, one in the middle, and the two others 

 formed by the produced angles of the terminal margin. 



[The investigation of the Ichneumonidae, since the death of Latreille, has been greatly attended to ; the great 

 work of Gravenhorst has made us acquainted with the Ichneumones genuini, or those which composed Latreille's 

 first division, whilst the Ichneumones adsciti, or those composing the two other divisions of Latreille, have been 

 described by Dr. Nees Von Esenbeck, Professor Wesmael of Brussels, and Mr. Haliday, in various memoirs and 

 separate publications, in which a great number of genera are added to those noticed in the text.] 



The third tribe, Gallicol^ {Diploleparice, Latr.) has only a single nerve in the hind wings ; the upper 

 wings possess a few cells or areolets : namely, two brachial cells at the base, the internal one beiu"- 

 generally incomplete or but slightly distinct, one radial and triangular, and two or three cubital ; the 

 second in those which have three, being always very small, and the third very large, triangular, and 

 closed by the external margin of the wing. The antennae are thickened at the tip, but not forming a 

 mass, and mostly from 13- to 15-jointed; the palpi are very short, [not very long, as described by 

 Latreille]. The ovipositor is rolled spiraUy up in the interior of the abdomen, with the posterior 

 extremity lodged in a slit of the belly ; the Gallicolse form the genus 



CvNiPS, Linn., — 



Which Geoifroy inconsiderately named Diplolepis, and gave the name of Cynips to insects of the 

 following family, united by Linnaeus with the terminal di\ision of the Ichneumons. 



The abdomen is compressed, the thorax very much elevated, the ovipositor of the females appears to 

 consist of a single long and very delicate piece, rolled up spirally at the base, and the terminal part 

 being lodged beneath the anus, between two elongated valves, each forming a demi-sheath. The 

 extremity of this ovipositor is channelled with lateral teeth, with which the insect enlarges the slits 



