114 ILLINOIS BIOLOGICAL MONOGRAPHS [114 



the order in which they seem to have arisen ; first the primary setae, 

 then the development of verrucae, which later became modified either 

 by the addition of numerous secondary setae, or by reduction to almost 

 the primary chaetotaxy again. In the absence of justification in adult 

 structure, it does not seem best to separate the last three groups from 

 the first as a distinct family, as has been done by some previous workers. 



Family Agaristidae 



This family should meet the same fate as Nyeteolidae and be in- 

 cluded among the noctuids. The adult structure on which it is based, 

 the clubbed antennae, is so variable that it is hard to limit the group 

 exactly. At the same time the larvae seem to be distinguishable from 

 the Noctuidae only in color, nearly all the species being transversely 

 striped. The one species found east of the Rocky Mountains and north 

 of Florida, Alypia octomaculata, may be recognized by the humped 

 eighth abdominal segment, the conspicuous chalazae and the transverse 

 stripes. That is the extreme, however, for the western species form a 

 nearly complete series connecting Alypia with typical Noctuidae. The 

 following species were examined: Alypia octomaculata, A. langtonii, 

 A. ridingsii, Copidryas gloveri, C. cosyra Druce, Androloma mac-cul- 

 lochii. 



Family Arctiidae 



Head smooth, bearing sparse secondary setae or none ; front about 

 as wide as high, extending half way to vertical triangle ; labrum with a 

 rather wide, shallow emargination, sometimes acute at bottom ; ocelli 

 various, the fifth and sixth distant from the others. Body bearing 

 verrucae except in a few reduced genera, Doa and Utetheisa, in which 

 only primary setae and a few others remain ; usual positions of verrucae 

 shown in Figs. 25 to 28, 33, and 34. Verrucae of Beta and Rho groups 

 of mesothorax and metathorax never fused; Kappa of abdominal seg- 

 ments 1 to 8 always distinctly present near spiracle, sometimes, but 

 rarely, slightly lower on segment 7 than on segments 6 and 8; prolegs 

 with uniordinal crochets in a mesoseries, heteroideous in all but a few 

 species. (Fig. 107.) 



The author is not satisfied with the following table of the genera 

 but presents it in the hope that it may be of some service. Arctian 

 larvae seem not to possess constant characters of generic value, 



a. Verrucae reduced to chalazae bearing single setae. 



b. Head and thorax normal in size ; crochets heteroideous. Utetheisa 

 bb. Head very small, thorax swollen ; crochets homoideous. Doa 



aa. Verrucae not reduced, multisetiferous. 



