NORTH AMERICAN ACROLOPHIDAE — HASBROUCK 507 



lent character for the identification of that species. The eyes of 

 some species are quite heavily lashed, while those of others are entirely 

 without lashes. 



In many species, minute hairs or setae arise between the facets of 

 the compound eyes. Although these setae may be short or long, 

 they are invariably very slender and dehcate; in pinned specimens, 

 they are extremely brittle and may easily be broken off. The setae 

 are normally erect and linear, although they are recurved and recum- 

 bent in the cressoni-maculijer-crescentellus species group. The com- 

 pound eye may be very densely setose or entirely naked. It may 

 exhibit any of a number of transitional forms between these two 

 extremes, depending upon the particular species selected for study. 

 The eyes of several species exhibit a very sparse scattering of extremely 

 minute setae. Setose eyes are normally associated with elongate 

 labial palpi, but there are a number of exceptions. As a rule, naked eyes 

 are associated with palpi which are short or intermediate in length. 

 Typically, the setose eye is associated with the bifurcate uncus and 

 the naked eye with the simple or undivided uncus, although there 

 are a number of exceptions in both cases. 



THE ANTENNAE 



The general structure of the antennae in the Acrolophidae has been 

 described in the foregoing characterization of the group. The simplest 

 type of antenna, exhibited by many species, is that in which the seg- 

 ments are short and robust with a globular or beadlike appearance. 

 A somewhat more complex type, also exhibited by a number of species, 

 is a laminate antenna in which each segment has a ventral, quadran- 

 gular extension that appears flattened and platelike in lateral aspect. 

 The most complex type of antenna, occurring in several species, is 

 the bipectinate type in which each segment bears two separate proc- 

 esses that arise independently from the antennal shaft and extend 

 lateroventrad. These processes are quite large and prominent, having 

 a tendency to enlarge toward their apices. 



Between these simplest and most complex types of antennae, a 

 number of intermediate or transitional forms occur among the acro- 

 lophids. Described in detail in the key and in the sections treating 

 the various species, the major types of these are (1) simple or globose, 

 (2) laterally flattened or laminate, (3) transitional between laminate 

 and unipectinate, (4) reduced unipectinate, (5) strongly unipectinate, 

 (6) showing moderate tendency toward bipectination, (7) reduced 

 bipectinate, and (8) strongly bipectinate. 



On the antennae of all species, on the dorsal portion of each segment, 

 are at least two rows of scales that overlap to furnish the antennal 



