220 STRATIOMYID.i: 



and with the third issuing veinlet bent down sharply and joining the upper branch 

 of the postical fork just before the wingmargin so that the fourth posterior cell is 

 closed ; postical fork simple except that each branch of the fork unites Avith the 

 neighboring vein just before the wingmargin, so that the anal cell is also closed 

 near the Avingmargin ; small cross-vein usually distinct but sometimes almost 

 absent ; wing-membrane minutely but distinctly pubescent, and with indistinct folds. 



Fig. IbG.^Xylomyia macvlata ? 



Alar squamae small and triangular, with a long but not dense fringe ; thoracal 

 squama3 absent. Halteres normal. 



The larvae resemble those of tSarr/iis, and live in the pulji or rotten wood debris in 

 hollows in many kinds of trees, or (it is said) on the out-flowing sap, especially 

 of Elms (Ulmus), Oaks {Quercus), Poplars (Popidns), and Walnut (Juglans). 

 Specimens of X. macidata are more easily obtained by breeding than by capture, so 

 much so that in places or even on trees where its larvae are abundant the perfect 

 insect is scarcely ever seen, and I believe its habits in the imaginal state are very 

 little known ; the female of X. margiimta has occurred on the trunks of felled trees, 

 and though active is not very shy. 



This genus is easily known among the Stratiomyidm by its Ichneumon- 

 like appearance, its venation, and its spurred posterior tibiae, but with the 

 Leptid subfamily Xylophagince (with one of which it was for a long time 

 thought congeneric) the superficial resemblance is very close; so far, 

 however, as we are concerned in Britain the closed fourth posterior cell is 

 peculiar to Xylomyia. 



Xylomyia is at present composed of very few species, and only three or 

 four have been met with in Europe, though closely allied species occur in 

 Caffraria, Sierra Leone, the Canaries, North America, and South Asia. 



Synonymy. — This genus was known from 1820 to 1861 as Suhda Meig., but as 

 that name had been preoccupied by Schumacher in 1817 for a genus of Mollusca 

 Rondani substituted Xylomyia ; the change was received with very little favour by 

 dipterologists and even in 1886 Osten Sacken declined to adopt it on the ground 

 that " a change in a name of such old standing involves much more inconvenience 

 " than its retention ; " I have however made close inquiry and I find that 

 Schunracher's genus is well established and in general use in Mollusca at the present 

 time, and therefore I fear that the inconvenience of the change must be endured. 

 Williston's substitution of the name A'?;&i//o?/i»//a in 1896 was made hastily without 

 noticing that Rondani had proposed Xylomyia thirty-five years previously. 



The type of the genus Sulnda would apparently be *S'. macidata Meig. because 

 that is the species that Meigen figured, and is the first species of this section of 

 ]\reigen's genus Xylojdiagvs, and is the only one to which Meigen has actually united 

 ]\[egerle's generic and specific names (though Meigen received all three species from 

 Megerle with suggested names) ; Rondani however when proposing the name 

 Xi/lonij/ia in substitution for Suhula gave S. varia as the type, possibly because it 

 may have been the only species known to him. So long as X. macidata and 

 A^ varia remain in one genus it does not matter which is the type species, but in 

 case of any further subdivision of the genus (which is not unHkely) I leave the 

 matter to be adjudicated upon at that time ; before however any new name might be 

 proposed it would be well to ascertain further details about Solva of Walker which 

 was founded in 1862 and which has been sunk by Osten Sacken as a synonym. 

 The type specimen of Macroceromys Bigot (1879) has markings on the thora'x very 



