368 C. B. Osten Säcken: 



The naiiie is derived from tlie Greck iveQyö-;, active, stroug, in 

 allusion to the development of the legs of the corresponding Diptera. 

 (In coniposing tliese names I had the advice and assistance of the 

 distinguished Greek scholar. Prof. Stadtmüller of Heidelberg.) 



3. The Mydaidae will form a Superfamily for themselves. In 

 their peculiar structure they show no distinct relationship to any 

 family; they have no trace of macrochaetae; they belong principally 

 to the Southern hemisphere, where they seem to have originated, as 

 they do not occur in the immense Eurasian continent, except along 

 its extreme Southern outskirts. Among the families of Diptera, this 

 is an exceptional case of Isolation; the group seems to belong to an 

 earlier geological horizon. I form a separate Superfamily for the 

 Mydaidae, coincident with the family, and do not, for the pfesent, 

 propose a new name for it. — The geographical distribution of the 

 Mydaidae shows a striking analogy with that of the Parrots (Or- 

 der PsiUaci). The latter also from a well marked and natural group, 

 widely separated „from all othcr birds" (Wallace); they abound in 

 the warmer regions of the Southern hemisphere, and penetrate but 

 little into the South-Eastern region of the P^urasian continent. They 

 are a very antique race, „and not improbably date back beyond the 

 dawn of the Tertiary period" (Wallace). They are represented in 

 the temperate climate of New-Zealand by most specialized and extra- 

 ordinary forms: Nestor and the owl-like, nocturnal Stringops. 



I shall now give some further explanations about the Super- 

 families IVomöptera and Energöpoda. 



Tromüi)tera. The relationship of the Nemestrinidae, Cyrtidae 

 and Bombylidae is obvious, and has been noticed by the earliest 

 writers; it tinds its confirmation in the history of the transformation 

 of these families. They are all parasitic in their larval stages, 

 and, as far as known, all show two stages of development of the 

 larva, the mobile one after hatching, and the torpid, after roaching 

 their intended host. The Cyrtidae and Nemestrinidae, both acheta^) 

 (that is without macrochaetae), are specialized types, the former, 

 as far as known, are parasites of spiders ; the Nemestrinidae are 

 not universally distributed, but occur sporadically in disconnocted, 

 limited areas, far distant from each other, and characterized by a 



^) In may E?say etc. (1884) the term eremochaeta has not re- 

 ceived an exact definition, and I have wronfjly applied it to families 

 like the Syrphidae (on p. 499) and Bomhylidae (p. 501). The term 

 must be restricttd to the Supeifamil}' of that name, and occasional 

 cases of want of macrociiaetae in other families, sliould be better called 

 acheta, a term wbich has nothing to do with the latin Acheta, cricket. 



