178 BRITISH ICHNEUMONS. \Pezomnchus. 



the basal area. Scutellum of 5 not discreted from the mesonotum and 

 usually entirely wanting. Terebra not shorter than half the liasally con- 

 stricted first segment. Penultimate tarsal joint not deeply incised nor 

 bilobed. Female apterous ; $ apterous, brachypterous or macropterous ; 

 wings, when macropterous, with the basal nervure strongly curved and 

 usually with the stigma very broad. 



The entirely apterous females and males, or, when the latter are winged, 

 their curved basal nervure, will distinguish this group of species from the 

 very closely allied Jlemiieloides^ among which some of the unassociated 

 $ $ may be referable to the present group, since both Gravenhorst and 

 Forster were of the opinion that their males were, like the females, always 

 entirely apterous or with no more than the minutest vestiges of wings. 



In 1878 Bridgman wrote, "There is a genus concerning which informa- 

 tion is much wanted ; that is the apterous little Cryptids of the genus 

 Pezomachus, which greatly resemble ants " (Entom. p. 35). The information 

 referred to was mainly in the association of the sexes and in the synonymy. 

 It has been acknowledged on all hands that Gravenhorst erected too few 

 species, considering (very wisely) that it were better to treat slight diver- 

 gences of structure and especially colour as mere varieties ; and that 

 Forster on the other hand (very foolishly) described as distinct every 

 traceable difference of every sort. The result of the latter method has 

 been the crowding of catalogues with " names," many of which differ from 

 each other in trivial and quite immaterial points. In 1870, Marshall had 

 to record thirty-five British kinds ; in 1872, the total had risen to forty- 

 eight "species"; and in 1883, Bridg.-Fitch enumerated sixty-one. When 

 compiling my total for the Entomological Society in March, 1901, I had 

 to bring forward twenty-nine more, thus showing ninety of Forster's 158 

 species, with a few of Thomson's and Bridgman's, from our Islands. 

 The strange thing is that no one ever attempted to synonymize Fbrster's 

 trivialities, except Thomson, who, in 1884, found several to be alike. It 

 has consequently devolved upon me to reduce the great mass as far as is 

 consistent with the specific characters, among which it is very difficult to 

 determine which are constant (for I am persuaded the development of the 

 scutellum and continuity of the abdominal pubescence is dependent on 

 larval nourishment), and the great divergence of the sexes. 



In this I have been very greatly aided by Mr. E. A. Elliott, who has 

 placed in easily comparative form the whole of the European females, and 

 who has studied the genus for the last seven years. Even he, however, 

 quite failed to recognize characters sufficiently valid to compose a table of 

 the species. Forster divided them primarily upon the presence or absence 

 of the transverse metathoracic carina, taking the apophyses to indicate a 

 ridge in such cases as might be ascribed to either, but he himself has 

 introduced many exceptions to this rule, and the development of this 

 carina is very variable and a most unsatisfactory feature, as also is the ap- 

 proximation of the puncturation, another point upon which he much relies. 

 It became essential, therefore, to promulgate a new scheme of specific 

 distinction ; and this was tentatively outlined in the E.M.M. 1900, p. 147, 

 having the length of the antennae, of their individual joints, the sculpture 

 of the abdomen, the presence of the scutellum and conformation of the 

 basal segment as its primary points. Of these it was found impossible to 

 employ the relative length of the antennae, though that of their joints is 



