2 PROCEEDINGS OF THE NATIONAL MUSEUM vol. TO 



A brief summary of the habits of the larvae of each species is given 

 under the species. The larvae show many more variations in form 

 and structure than do the pupae, and I think that this is probably 

 explained by their adaptation to the more various ecological situa- 

 tions. 



The principal character used in the description of the larvae and 

 pupae is the spiracular plate, and from an examination of all the 

 material before me this seems to be a very constant character. The 

 spiracular plates in all of the species, except that belonging to the 

 genus Verfnileo, are very similar, and in all the spiracular entrance, 

 or so-called spiracular opening, closely resembles the script capital 

 letter " E." There is. however, sufficient variation in the location, 

 form, and size of the spiracles to offer very useful diagnostic 

 characters. 



Some of the principal characters used are the following: 



/Spiracular entrance (pi. 2. fig. 9r). — This term means the main 

 spiracular opening which contains numerous small openings called 

 the slits. 



Peritreme (pi. 2, fig. 9^'). — By this term is here meant chitinous 

 ridge or elevation which directly limits the spiracular entrance. 



Basal. — This term means the end of the abdominal segment toward 

 the thorax. 



The material available make it possible to prepare the following 

 family diagnosis : 



L&rva. — Generally cylindrical, smooth, white to pale yellow and 

 Avith or without prolegs; head pointed and heavily chitinized or 

 only partially chitinized; posterior spiracles located on the surface 

 and no posterior cavity. Or the larva is depressed, gray-broAvn in 

 color, the entire surface covered with scale-like plates; posterior 

 spiracles in a cavity which opens transversely but generally is closed 

 and forms a linear depression. 



Pwpa. — Tj'pically orthorrhaphous in form with the antennal cap- 

 sules large and located on the anterior edge of the head; these cap- 

 sules are free from the head on their apical half or more. Or the 

 antennal capsules may be small, slightly raised on the surface of 

 the head, giving to the head the appearance of being bent down- 

 ward. The spiracular plates closely resemble each other but vary 

 m size from quite small to large. 



LARVAE 



TABLE OP SPECIES 



1. Larva entirely chitinized and sliglitly flattened; surface reticulate. 



(No. 1) Xylomyia pallipes Loew. 

 Larva not as above 2 



2. Head elongated, iwinted, heavily chitinized 3 



Head not as above 5 



