Dipterous Genus Xylomyia, Bond. 183 



Mg., with the abdomen, with the exception of the semilunar 

 depression at the base, entirely black and without the in- 

 cisions between the segments being " very narrowly yellow," 

 as described by Meigen *. As is unhappily the case through- 

 out the Stephensian Collection, these three specimens are 

 without locality-labels. Xylomyia maculata as a British 

 insect was also known to Westwood, for in the l Introduction 

 to the Modern Classification of Insects,' vol. ii. (1840) p. 534, 

 he writes : — " The Rev. F. W. Hope has also given me 

 specimens of Subula maculata and its preparatory state ; the 

 latter found by him in a dry rotten tree in the New Forest, 

 and from which he reared the imago. It is larger than that 

 of X. varia, but does not otherwise differ from it." It will 

 have been noticed that all the British examples of Xylomyia 

 maculata hitherto recorded come from the same locality. 



In Verrall's ' List ' the genus Xylomyia is placed with 

 Xylophagus, Mg., in the family Xylophagidse ; in Schiner's 

 ' Fauna Austriaca ' the same family is made to include a 

 third genus, Pachystomus, Latr. (for Rhagio syrphoides, Pz.), 

 which is stated by Osten Sacken (Berl. ent. Z. xxvi. (1882) 

 p. 379) to be " nothing but a Xylophagus with broken an- 

 tenna?." While, however, the differences between Xylomyia 

 and Xylophagus are of more than generic rank even in the 

 perfect state +, in the preliminary stages they are much more 

 marked. Whereas the larva? of Xylomyia as well as of 

 Xylophagus live in the stumps and beneath the bark of dead 



* Xylomyia varia, Mg., is a considerably smaller species than. X. macu- 

 lata, measuring only 5-3 to 7'3 milliin. (3 to 3-5 lines) in length, instead 

 of 9 - 3 millim. (4-5 lines), but the antennae are longer ; the dorsum of the 

 thorax is without yellow markings, and the legs, except the tips of the 

 tarsi, are yellow. Xylomyia maryinata, Mg., is not represented in either 

 of our collections of British Diptera ; but two ( § ) specimens from 

 Germany in our general collection of Diptera show that, while agreeing 

 in length with X. varia, it is a much broader and bulkier insect, and con- 

 sequently, as regards size, occupies an intermediate position between 

 X. maculata and X. varia. The antennae are shorter than in the latter 

 species ; the thorax is without yellow markings on the dorsum and is 

 not shining, being finely and closely punctured and clothed with very 

 short yellowish hair, forming indistinct longitudinal stripes ; the hind 

 margins of the abdominal segments from the second to the fifth are 

 narrowly yellow ; the legs are yellow, with black coxes, and the ends of 

 the tarsi and the tips of the hind femora infuscated; the hind femora are 

 ■distinctly swollen (which is not the case in the other two species), and 

 bear a row of minute black tubercles on the distal half beneath ; the vena- 

 tion is as in X. varia. In X. maculata the upper branch of the third 

 vein is distinctly more slender than the main stem, and is shorter and 

 flatter than in the other two species, while (as pointed out by Schiner) 

 the first vein that leaves the discal cell is very strongly curved. 



t Cf. O. Sacken, Berl. ent. Z. xxvi. p. 364 (referred to by Brauer, 

 Denks'chr. k. Akad. Wiss. Wien, Bd. xlvii. p. 23, note). 



