NORTH AMERICAN ACROLOPHIDAE — HASBROUCK 497 



In selecting a group or combination of characters for generic separa- 

 tion of the Acrolophidae, there is found a singular failure of any one 

 character to reinforce consistently any other character among the acro- 

 lophids. For example, elongate labial palpi and setose compound 

 eyes usually may be associated with one another. In general, as the 

 palpi become longer the eyes become more heavily setose, and, con- 

 versely, as the palpi become shorter the eyes become more sparsely 

 setose. However, several species exliibit the combination of greatly 

 elongated labial palpi and naked compound eyes, while several others 

 exhibit a combination of shortened palpi and densely setose eyes. 

 Thus, the combination of eye and palpus must be discarded as a 

 generic character. 



The same situation exists among the genital organs. Generally, the 

 bifurcate uncus is associated with the paired gnathos, the simple uncus 

 with the fused gnathos, and both organs tend to show a like amount of 

 fusion or separation in any one species. However, at least one species 

 exhibits the combination of a simple uncus and a strongly paired 

 gTiathos. Conversely, another species exhibits a bifurcate uncus and a 

 fused gnathos. Thus, the morphological chaages of these two organs 

 from species to species are not always in harmony, and the combination 

 of uncus and gnathos fails to afford a means of generic separation. 

 Cephalic and genital structures may Ukewise be compared Avithout 

 success. The setose compound eye may commonly be associated 

 with a bifurcate uncus and a paired gnathos, and the short labial palpus 

 is most commonly associated with the simple uncus and the fused 

 gnathos, but to each there are notable exceptions. When four or 

 more characters are used in combination in an attempt to make a 

 generic separation the situation simply becomes more complex and 

 muddled. 



From these observations it is apparent that at the generic level any 

 single character becomes an intergrading character, and any number of 

 characters in combination, fail to reinforce one another. But, al- 

 though every possible proposal for separating the Acrolophidae into 

 two or more genera is met with "exceptions to the rule," this situation 

 provides the worker with a wealth of excellent, nontntergrading 

 characters for the separation of the numerous species. 



When all of the species of Acrolophidae have fuially been diagnosed 

 and placed in proper sequence, natural genera wiU undoubtedly emerge 

 from such nuclei as the species groups described in this revision, and 

 they will be based upon rather subtle combinations of numerous 

 characters. To diagnose and assign limits to these genera once their 

 specific components have been found and set into place, will be much 

 easier and also much wiser than to set up arbitrary, and probably 

 faulty, generic categories now, in the hope that subsequently dis- 



