300 PROCEEDINGS OF THE 



What may be the name of the Saw-fly which produces it I cannot 

 say for certain till the fly appears. The larva becomes slate- 

 coloured when it has reached its third moult. 



II. — On tlie British species of the genus Croesus. By the same Author. 



The genus Crcesiis was founded by Leach in volume iii., p. 129, 

 of his Zoological Miscellany, on the Tcnihredo septentrionalis of 

 Linn6. The principal mark of distinction between it and Nematus 

 lies in the hinder tibiae and the first tarsal joint being greatly 

 enlarged and compressed. Otherwise it agrees perfectly with 

 Nematus; and even some typical species of the latter genus have the 

 hinder tibiae dilated, though perhaps not to so great an extent. 

 The majority of systematists have therefore considered it to be 

 merely a section of Nematus. The species composing it are very 

 like in coloration, the abdomen broadly banded with red, and 

 the feet variegated Avith red, black, and white. Further, the 

 larvae exhibit a striking peculiarity, namely, in possessing seven 

 glands on the under side of the abdomen, between the claspers, 

 and which glands they are able to protrude at will. Their use is 

 clearly to frighten away ichneumons and other enemies. The 

 larva feeds quite exposed and conspicuously on the edge of the 

 leaf; and whenever anything approaches the body is flung about 

 in all directions, often over the head, thus exposing the abdominal 

 ducts, which are freely protruded. But even with this protection 

 they do not escape from parasites. 



Four species have been described, namely; C. sejitentrionalis, by 

 Linn6 ; and latijjes, latlcrux, and varus, by Folques de Villaret. Of 

 these Stephens describes, in his " Illustrations of British Ento- 

 mology," vol. vii., pp. 38 and 39, septentrioiudis, varus, and laticrux; 

 but he seems to have been in doubt regarding varus ; and Mr F. 

 Smith; in his " Nomenclator of Hymenoptera," only records the 

 first mentioned ; so that -it lool« either that Stephens had not 

 the proper insects, or, if he had, that Mr Smith himself regards 

 them all as varieties of septentrionalis. For nay own part, I can 

 only look upon laticrux a^ a variety o{ septentrionalis ; and^I have a 

 specimen that agrees very closely with its description; but we 

 now know from the discovery of the larvae of varus and latipes 

 that those two are good species ; and I have, moreover, good 

 evidence that latipes, which Stephens does not mention, is a 

 British insect. 



