Dipterous Genus Xylomyia, Bond. 187 



rium is no mere accidental occurrence ; on the contrary, it 

 appears to be invariable in the genus Xylomyia. It was 

 recorded seventy years ago by von Roser (Joe. cit. p. 190) in 

 the case of Xylomyia varia (Xylophagus varius), Mg., and 

 one of von Roser's specimens showing this was given by him 

 to Westwood, who mentions it in the ' Introduction ' (vol. ii. 

 p. 534), and illustrates it by a (very poor) figure (op. cit. 

 p. 531, fig. 127, h). Dufour, who bred some forty specimens 

 of his species Subula citripes, actually witnessed the partial 

 emergence of the pupa from the puparium and the subsequent 

 escape of the fly ; he describes how the pupa works its way 

 out through the rent in the thoracic segments of the larva- 

 skin until two thirds of its length project, and states that the 

 " domino de la nymphe " may be found in the rent after the 

 imago has left it*. Lastly, Tovvnsend writes (loc. cit. 

 pp. 163, 164) of Subula pallipes, Lw. : — " The pupa works 

 itself more than halfway out through this opening [in the 

 puparium], and there remains. The fly then escapes, 

 leaving at least the posterior one third of the pupal skin still 

 enclosed within the split portion of the puparium." 



II. 



Systematic Position. 



So long ago as 1882 it was shown by Ooten Sacken that 

 Subula (Xylomyia) could not be allowed to remain in the 

 same family as Xylophagus, where most of the previous 

 writers had been content to leave it, but that the original 

 family Xylophagidse must be dissolved, Subula being placed 

 " among the Beridina, until its relationship is cleared up." 

 Osten Sacken proceeded to say : — fl Xylophagus and Cceno- 

 vnyia would form the stock of the reformed family Xylo- 

 phagidse, which must be brought in nearer connexion with 

 the Leptidse, and not with the Notacautha " "j\ Shortly before 

 this Brauer had been led to a similar conclusion through 

 study of the larvas ; he wrote % : — " In the Xylophagidse we 

 find two divisions, of which one (Subula), through the larva 

 and its mode of pupation, reminds us of the true Stratiomyidse, 

 while the other (Xylophagus) recalls Tabanidse and exhibits 

 a free nymph." The remarkable external resemblance be- 

 tween the larvseof Xylomyia and those of certain Stratiomyids 



* Ann. Sc. Nat., Zoologie, s<5r. 3, t. vii. (1847) pp. 10-11, t. vi. pl.xvii. 

 fig. 18. 



t C. R. Osten Sacken, " On Professor Brauer'a Paper : Versuch einer 

 Characteristik der Gattungen der Notacanthen, 1882," Berl. ent. Z. 

 Bd. xxvi. (1882) p. 365. 



J Denkschr. k. Akad. Wiss. Wien, Bd. xliv. (1882) pp. 61-62. 



