346 PROCEEDINGS OF THE NATIONAL MUSEUM vol. iii 



foliaceous lobe on segment II. The head bears two types of vestitures. 

 The first type is the primary setae, which arise from a series of punc- 

 tures and appear to be a constant and basic feature of nearly all species 

 except those in Sehirus. There are usually tliree primary setae present, 

 one on the apical half of each jugum, one anterior to the inner half 

 of each eye, and one in the lateral angle of the preocular part of the 

 head (fig. 43), or there may be more present as in Amnestus, which 

 has four (fig. 59), or fewer as in Ectinopus, which has two (fig. 66), 

 or there may be none, as in Sehirus. The secondary type of vestiture 

 shows considerable generic and specific variation and consists of a 

 variable row of setigerous punctures that may extend from the eye 

 to the apex of the head where the tip of the clypeus is involved, or 

 the row may be partial or reduced to a single setigerous puncture 

 anterior to the eye. This single puncture is, in reality, the lateral 

 primary puncture, but because it is usually incorporated in the row 

 of secondary submarginal setigerous punctures, it may be discussed 

 more clearly as a member of that series. The setae that arise from these 

 submarginal punctures may be long, slender, and liaulike, referred to 

 here as "hairs," or they may be short, stout, and blunt, referred to as 

 "pegs"; interpretation of these types of submarginal setae is difficult 

 because the burrowing habits of tlie insects may cause the hairs to be 

 broken off near the base and the remaining part will be short and blunt, 

 suggesting the pegs. The absence or presence of ocelli in American 

 Cydnidae appears to be a specific feature, as does the location of the 

 ocelli in relation to the eyes, the surface sculpture, the length of the 

 antennal and labial segments, the relative lengths of the juga and 

 clypeus, and the development of the bucculae. 



The features offered by the prothorax, except for the presence or 

 absence of a sharply impressed, subapical line paralleling the anterior 

 margin from side to side, appear to be chiefly of specific value. In 

 several genera certain species show a sexual dimorphism in that the 

 lateral margins of the male pronotum are noticeably constricted, 

 while those of the female are entire. Although such a feature might 

 be conspicuous, it is extremely variable within the group, and often 

 within one species; because this feature appears of questionable 

 survival value and surely of no phylogenetic significance, it should 

 not be accorded more than specific importance. Most species other 

 than those of the genus Sehirus present a lateral, submarginal row of 

 setigerous punctures. The arrangement and number of these setiger- 

 ous punctures furnish good specific features. The pronotal surface 

 is divided into an anterior and posterior lobe by a more or less distinct 

 transverse impression near or behind the middle. The anterior lobe 

 is often modified in the males; it may be tumid and/or variously 

 impressed medially near the apex. The posterior lobe shows a 



