52 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 5 1 



latter. They doubtless represent a branch which sprung from the 

 proto-Myodarian stem during its period of multiform development. 

 They should be considered as one of the primary divisions of the 

 Holometopa, probably equal in taxonomic rank to all of the other 

 Holometopa taken together. They stand in practically the same 

 relation to the Holometopa as do the CEstridae to the Schizometopa, 

 the QEstridse also being a group apart from the other Schizometopa 

 and of older origin. Moreover, the CEstridae is a polyphyletic 

 group showing affinities with various subfamilies and tribes of Mus- 

 coidea, but owing to its present preponderance of characters due to 

 mode of life it is best treated as a family. For similar reasons the 

 Conopidae are also best treated as of family rank. 



While on the subject of the relationships and extreme specializa- 

 tion of the Schizophora in general and the Muscoidea in particular, 

 it becomes highly significant to note that the Muscoidean stock has 

 originated three separate and distinct types of parasitism on mam- 

 mals, all having the same end in view— that of nourishing their 

 larvae at the expense of Mammalia — but each of the three attaining 

 this result in radically opposite ways. 



Cutcrcbra and its allies attain this end by their well-known sub- 

 cutaneous larval endoparasitism, in which the larva does all the 

 feeding, the imago taking no nourishment whatever, this peculiarity 

 being developed even to the extent of the adult mouthparts having 

 become atrophied and nonfunctional. 



Glossina secures the same result by a supracutaneous imaginal 

 ectoparasitism, in which the adult does all the feeding, by actual 

 mechanical blood-letting, and retains and nourishes the larva within 

 the oviduct until it is fully grown, when it is extruded and becomes 

 a pupa almost immediately and absolutely without feeding. This is 

 the exact antithesis of the preceding. 



But the Muscoidea must be credited with developing yet a third, 

 and still more remarkable method, because wholly unique and unpar- 

 alleled among dipterous larvae of this description, of living at the 

 expense of mammals. Auchmeromyia produces a bloodsucking 

 larva, and thus furnishes a case of supracutaneous larval ectoparasit- 

 ism, since the larva sucks blood externally by mechanical means. 

 This is the so-called Congo floor-maggot, which has recently 

 attracted some attention in the literature. It possesses an extended 

 range on the West African coast and has also been reported from 

 Uganda. The maggot-like larva pierces the skin of sleeping per- 

 sons with its small but sharp jaws, and sucks their blood. It is an 

 unique habit, because the larva is a footless maggot with extremely 

 small jaws and no means of attaching itself to the skin of its host 



