46 
The single North American species, tenebrifera Wlk., which is included 
in this genus, differs from the type in the shorter vestiture of the palpi, the 
bipectinate antennse, and the intermingling of numerous forked hairs in 
the thoracic vestiture. The genitalia, however, are very similar, with the 
characteristic scobinate flaps to the anellus. The vesica is armed with two 
long cornuti instead of the single one of rubricosa. 
Figure 24. Male genitalia of Ceraslis tenebrifera Wlk. 
These differences are believed to be merely of specific value; in any 
case, for those who wish, we have the term Matuta Grt. available for tene- 
brifera. 
Peridroma Hbn. 
1822, Verz. bek. Schmett. 227 (type, margantosa Haw.). 
Eyes naked. Palpi upturned, the third joint porrect; second^joint 
rather roughly fringed with scales and hair beneath and with distinct 
triangular apical tuft; third joint with rather rough vestiture. Front 
smooth. Male antennae shortly fasciculate. Tibiae all spined; fore tibia 
slightly longer than first tarsal joint, smooth-scaled, with a broad curved 
fringe of scales and hair on outer side partly concealing the few apical 
spines; inner margin with a complete row of weak spines. Mid tarsi with- 
out fourth row of spines. Thoracic vestiture scaly with well-developed, 
divided, pro- and metathoracic tufts. Abdomen rather flattened. 
Male Genitalia. Clasper of average length with strong corona; harpe 
slightly excurved and projecting over costa, attached at base to a broad 
foot of chitin, the proximal portion of which is contiguous with the fairly 
strong saeculus; ampulla present. Clavus a very minute tubercle. Uncus 
bulbous at base, drawn out to a fine and slightly recurved point apically. 
Juxta a heavily chitinized plate, the medio-apical portion strongly bulging 
and armed with a sharp spine. Aedoeagus armed with apical chitinous 
plate, one edge of which is drawn out to a sharp tooth with dentate edge. 
