PUPIPARA. 



79 



at all retractile. The body is more or less flat, the abdo- 

 men indistinctly segmentated in most cases and leathery 

 in appearance. The legs are always stout, sometimes 

 much elongated, with strong and stout claws, which may 

 have an strong pectination in addition to the enlarged 

 basal part. In their breeding habits all are believed to 

 be pupiparous, that is giving birth, not to eggs or even 

 young larvae, as is the case with nearly all other diptera, 

 but to larvae just ready to transform into puparia, an 

 evident adaptation to their peculiar enviromental condi- 

 tions. The wings, as would be supposed, are often ves- 

 tigial or wanting, and in many cases the venation has 

 undergone degeneration. But a single form is known to 

 be parasitic upon other insects, bees, of a family hitherto 

 unknown to occur in America. 



Because of these marked and peculiar habits, and the 

 structural characters, some recent writers are inclined to 

 raise the rank of the group to a subordinal value, making 



it equivalent to all the other diptera combined. To this, 

 however, I am decidedly opposed. The flies seem, with 

 hardly a doubt, to be merely degenerate descendants of 

 the Muscids, and probably of the acalyterate division. 

 The venation of such forms as Raymondia is characteris- 

 tically acalypterate; in some others there has been, ap- 

 parently, an elongation of the first and sixth veins, and 

 an enlargement of the basal cells. Schiner long ago 

 described a psculiar type with reduced wings, parasitic 

 upon hawks, which he placed among the acalypterates 

 in the vicinity of the Borboridae, and it does not seem un- 

 likely that this is the real relationship of the whole group. 

 Very similar structural adaptations are observed among 

 the parasitic and wholly unrelated Phoridae — bristly, re- 

 duced antennae, loss of eyes and wings, leathery abdomen, 

 stout legs, etc.; or among the tsetse flies — distinctly pu- 

 piparous habits. The most that I am willing to concede 

 to the Pupipara is a rank equivalent to that of the Myoda- 

 ria. The group is a comparatively recent one geological- 

 ly, in all probability. 



