1. XYLOPHAGUS 247 



his genus upon a knowledge of that species, and as he described the Ijasal joint 

 of the antennae cylindrical (walzenformig) as compared with the cup-shaped second 

 joint, and in 1804 placed X. ater as his leading species, it may be concluded that 

 the latter species is the type of the genus. Meigen sometimes too hastily gave 

 a species of DeGeer as typical of a genus when he believed that he compre- 

 hended the species from specimens before him which were however not identical 

 with DeGeer s species, and in such cases the type of the genus cannot be 

 DeGeer's species, e.g. Corethra was a genus well designed by Meigen but Tipida 

 cxdiciformis DeGeer being unknown to him could not have been the type of it, 

 and therefore in that and other genera it becomes necessary to find out what 

 species Meigen had before him before fixing the type species. Meigen did know 

 Xylo2^hagi(s ater and did not know Xyl. cinctus, and consequently if Xi/l. 

 cinctus could by any chance be placed in a distinct genus a new generic name would 

 have to be formed for it, and not one for X. ater. In 1820 Meigen placed the 

 species of our present genus Xylo7m/ia in a separate section of his genus Xi/Iojihagvs, 

 and stated that Megerle had suggested the name Subula for them, and consequently 

 they lose all claim to the name Xylophagus. As a matter of fact DeGeer's figure 

 of " Nemotelus cinctus " is unmistakably that of a female Xyloj^hagus cinctus. There 

 is another point to be reckoned with in dealing with Meigen's genera which were 

 indicated in Illiger's Magazine in 1803 ; Meigen only gave short characteristics of 

 a hundred and fourteen genera, of which about ninety were new to science, yet in 

 many cases he indicated no species as representative of the genus, and in these cases 

 in all probability he only knew undescribed species, but in other cases he mentioned 

 some already described species (even if unknown to him) as probably belonging to his 

 new genus but not necessarily was typical ; the paper was also only issued as a trial or 

 experiment (Versuch) and was onljr the precursor (Vorlaufer) of his subsequent work ; 

 I therefore attach no value to the indicated probable representatives (not the types) 

 of Meigen's new genera in that paper, but I accept as types those species which were 

 indicated as such in Meigen's next work. Pachystomtis of Latreille (1809) was obvi- 

 ously founded upon a female Xylophagus cinctus with deformed antennae, which 

 had previously been described and figured by Panzer under the name of Rhagio 

 syrphoides. 



Table of Species. 



1 (2) Basal joint of antennoe cylindrical, four times as long as the 



second (fig. 180). Thorax considerably shining. Abdomen 

 of the female not at all reddish. 1 ater. 



2 (1) Basal joint of antennae rather globular, not twice as long as the 



second (fig. 181). Thorax dull except about the humeri. 



Fig. \%(}.— Xylophagus ater i . x 20. Fig. ISl. —XT/lophagiis dnctus <S. x 20. 



Abdomen of the female conspicuously reddish about the 

 middle. 2 ci7ictus. 



A third European species occurred in Kowarz's collection under the label of 

 X. cinctus, which however I take to be undescribed ; the male of it may be 

 distinguished by its entirely shining frons and by the broad dull disc of the thorax 

 of which only the sides are shining black. 



1. X. ater Fabricius. Antennoe with the basal joint cylindrical, nearly 

 four times as long as the second. Thorax of the male mainly shining, but 



