1901.] 241 



AN ADDITION TO THE BRITISH STRATIOMYID.E, WITH THE 

 DESCRIPTION OP A NEW GENUS. 



BY ERNEST E. AUSTEN. 



Early in June of the present year I received from Dr. David 

 Sharp, F.R.S., a few small larvae or pupse of the usual terrestrial 

 Stratiomyid type, that is to say, presenting a close general resemblance 

 in external appearance to larvfe such as those of Xylomj/ia, Chloromyia, 

 or Microchrysn. They had been found by Dr. Sharp with a number 

 of others on June 1st, in a decaying holly tree at Bank, near Lynd- 

 hurst, in the New Forest. In length the adult larvae or pupae 

 measured some 0| mm., with a width of 1| mm. at their widest part 

 (5th post-cephalic segment), and owing to their narrowness I at first 

 expected that they would prove to belong to some species of Beris. 

 Since our knowledge of the life-history of this genus is still confined 

 to Walker's solitary statement, with reference to Beris chalj/heata, 

 Forst., that "the pupa had been found in moss,"* I rather hoped that 

 I was about to have the op])ortunity of to some extent filling up the 

 gap. The larvae or pupje were received on June Gth, and two days 

 later all doubts were set at rest by the emergence of a little shining 

 black fly, with a strikingly silvery looking thorax, which it was not 

 difiicult to identify as Pncliyqaster meroonelas (meromeJo'naf), Duf.,an 

 addition to the list of British Diptera. 



Other specimens subsequently emerged, and on June 1 1 th I 

 received a fresh supply of material from Dr. Sharp, including some 

 larvae which were smaller and paler than the rest, and evidently quite 

 young. In the end no less than eight flies made their appearance, 

 and among these were three males and five females. 



Before proceeding to the description of P. meromeJceno, it may 

 be as well to glance for a moment at previous statements as to the 

 life-history of species of Pacliygaster, which as it happens are fairly 

 frequent in dipterological literature. 



The larviB of Pachygaster appear to live exclusively in rotten wood. So long 

 ago as 1828 the larvae of P. ater (atra), Pz., were found by Schilling at the com- 

 mencement of spring beneath the bark of Pimts sylvestris — " in sylvaticis pagi 

 Lissae." These larvje, from which the imagines emerged within three weeks, were 

 briefly described and figured by Schilling (" Beitriige zur Entomologie," I. Heft 

 [Breslau, 1829], pp. 94-95, Taf. VIII, fig. 8). 



* Insecta Britaiinica, Diptera,, vol. i, p. 12 ;i851K 



t Since gaster is feminine, we must of course write Pachygaster meromelcena, atra. minu- 

 tisniixa, &.C., but for .some reason all previou.s authors, from Meigen to Osten Sacken, have given 

 specific names in thi.s genus a masculine termination. In the present paper a specific name 

 quoted for the fir.st time is written in the old way, followed, if necessary, by the cori'ect form in 

 brackets, and the latter is adopted in all subsequent references. 



