DIPTERA. — CENOMYIDE, 535 
I am inclined also to place, either in this family, or amongst the 
Cznomyidz *, several extraordinary genera which have much per- 
plexed entomologists in respect to their relations, such as Acantho- 
mera and Raphiorhynchus (gigantic Bgasilian species), and probably 
also Chiromyza Wied. and Agapophytus Guér. 

There remains, however, another family of great interest in regard 
to the transition nature of the species of which it is composed; and 
although I here retain it amongst the Notacantha, in respect to the 
spined scutellum and articulation of the terminal portion of the an- 
tennee, I cannot but consider that the differences in its transformations 
ought to induce its removal to the Tanystoma. This group, for which 
I propose the name of C&#noMyID#, comprises the genera Caenomyia 
and Pachystomus Zatr. (forming Macquart’s tribe Sicarii.+) The 
transformations of the former genus (which possesses 10-jointed an- 
tennz, and has from its singular characters been placed amongst the 
Tabanide, Stratiomidee, and Beridz) are not known, but Latreille 
has described the pupa of Pachystomus syrphoides (Genera, &c. 
tom. iv. p. 287.{) as closely resembling that of the Tabanide ; being 
consequently an incomplete, and not a coarctate, pupa. This genus 
has 5-jointed antenne. Meigen, not regarding this description, and 
unacquainted with the transformations of some other species closely 
related to this insect in the perfect state, retained the genus Xylo- 
phagus (previously proposed by him), the antennz of which (fig. 127. 
17.) are 10-jointed, and which he divided into two sections — A, having 
for its type Xylophagus ater § Meig. (vol.ii. pl. 12. f.4., and my jig. 
127. 16.), and B (or the genus Subula Megerle, above noticed), having 
for its type X. maculatus Weg. ‘The genus Subula, as discovered by 
M. Van Roser and the Rev. F. W. Hope, has a metamorphosis exactly 
like Sargus, the pupa being enclosed within the unaltered larva skin, 
but the transformations of the typical Xylophagi are quite different ; 
* Tt is from ignorance of the transformations of these exotic groups that I express 
this indecision. 
+ If the generic name Sicus be not retained for the former of these two genera, 
this name ought surely also to be rejected. 
¢ Zetterstedt also (Ins. Lapp. p. 513.) describes the pupa of this insect as 
“ elongata, cylindrica, subnuda, incisuris ciliatis et apiece breviter spinuloso, tota pal- 
lida, segmentis seu annulis 10 constare videtur.” . 
§ Latreille confused this specific name in the plates and text of his ‘ Genera’, and 
has retained his error in the Régne Animal. 
MM 4 
