48 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 5 1 



From the section Myodaria inclusive down to the families, and in 

 some cases the subfamilies, the divisions are particularly difficult of 

 exact definition, from adult characters alone, on account of the 

 numerous intermediates. A study of the characters of the early 

 stages is needed to determine beyond question the location of certain 

 intermediate forms. 



The family Macronychiidae includes those forms approaching - the 

 QEstridae in the character of the facial and peristomal development 

 of the head, and which have heretofore been classed partly with the 

 true tachinids and parti}" with the true dexiids. It corresponds prac- 

 tically to the group Macronychiidae of Brauer and von Bergen- 

 stamm, but it should be noted that Megaprosopus, and not Macro- 

 11 yc hia, is the real type of the family. 



The old family Dexiidae can not be maintained. With the excep- 

 tion of the few just mentioned as included in the Macronychiidae, 

 its forms all fall in the Tachinidae, of which they constitute several 

 subfamilies and tribes. 



Concerning the three types to be distinguished in the Muscoidea, 

 it may be pointed out that the most generalized type seems to be the 

 Phasiid. The primeval stock was the possessor of a Phasiid-like 

 facial-plate development, in all probability, more or less after the 

 Syrphoidean style. From this stock sprang the three present stems. 



Phasiid — Facial plate of the primeval type practically preserved, the meso- 

 facial plate and epistoma becoming solidly anastomosed into one piece, retain- 

 ing the characteristic bridge-of-the-nose production below. Both antennas and 

 mouthparts, especially the latter, well developed. 



Tacli inid-M itscid — Mesofacial plate much increased and epistoma more or 

 less reduced from the preceding, losing the bridge-of-the-nose production, but 

 retaining a more or less prominent oral margin, the mesofacial plate gaining a 

 length and width sufficient to accommodate the greatly developed antennae. 

 The epistomal development is largely retained to accommodate the very func- 

 tional mouthparts. 



(Bstrid-Macrony child — Mesofacial plate much reduced and epistoma (except 

 in Hypodermatinse) greatly narrowed and rounded off, losing the prominent 

 oral margin entirely. Antennae and mouthparts approaching atrophy from 

 disuse. 



The following detailed notes on the connectant forms appearing 

 to lie more or less between the superfamilies Muscoidea and Antho- 

 myioidea will be useful for comparison with the synoptic table just 

 given. The former superfamily includes the bulk of the old Mus- 

 cidae, the Sarcophagidae, Dexiidae, Tachinidae, et al. (Phasiidae, Gym- 

 nosomatidae, Ocypteridse, Phaniidae), and the CEstridae; the latter 

 superfamily includes the Anthomyiidae as herein accepted. The 



