Note K — Chapter XII · HOMINOXIOUS ARTHROPODS

There are several genera of flies of the family Cordyluridæ; (i.e. Acalyptratæ) which might be placed with the Anthomyiidæ (i.e. Calyptratæ), owing to the relatively large size of their squamæ. As there is no single character which will satisfactorily separate all doubtful genera of these two groups we must arbitrarily fix the limits. In general those forms on the border line having a costal spine, or lower squama larger than the upper, or the lower surface of the scutellum more or less pubescent, or the eyes of the male nearly or quite contiguous, or the eyes hairy, or the frontal setæ decussate in the female; or any combination of these characters may at once be placed with the Anthomyiidæ. Those forms which lack these characteristics and have at least six abdominal segments (the first and second segments usually being more or less coalescent) are placed with the Acalyptrates. There are other acalyptrates with squamæ of moderate size which have either no vibrissæ, or have the subcosta either wholly lacking or coalescent in large part with R1 or have spotted wings; they, therefore will not be confused with the calyptrates.