CYDNIDAE OF THE WESTERN HEMISPHERE FROESCHNER 457 



of convergence but rather a reflection of fundamental relationships. 

 And even the separation offered by the presence or absence of the 

 submarginal row of pegs on the head was in part bridged by the 

 discovery of a new species from North America which possessed a 

 partial row of submarginal pegs. Therefore, the two forms formerly 

 assigned to ^'Homaloporus'' must now be considered as members of 

 Pangaeus and the former name synonymized under the latter where 

 it is available for subgeneric naming as is proposed below. 



The combination of the two features given in the diagnosis above 

 sets this genus apart so sharply from other cj^dnid genera that it is 

 somewhat surprising to find that there has been some confusion 

 concerning its hmits. The emphasis formerly placed on the vestiture 

 of the head could justify the old separation of " Homaloporus" and 

 Pangaeus, but even so, the latter taxon was not clearly delimited in 

 other directions. The confusion actually started with Uhler's (1877) 

 assignment of his new species discrcpans to Pangaeus with the remark, 

 "the transverse line interrupted in the middle, remotely, coarsely 

 punctate." The type of discrepans has no collum or limiting impressed 

 line, thus, Uhler's statement that the line was "interrupted" has been 

 misleading. Not only was discrep)ans carried thus as a Pangaeus, 

 but another species, calif amicus, without a collum was described and 

 erroneously assigned to the genus by Blatchley (1929). Blatchley 

 did, however, recognize that both of these species were in the uTong 

 genus and suggested that a change would have to be made. In the 

 present study, both of these species have been transferred to the 

 genus Dallasiellus. 



From the studies on which this revision was based, from a close 

 examination of Signoret's revision, from Distant's (1899) attempt to 

 clarify the status of Walker's several species, and from notes on the 

 types in several museums it is clearly evident that there has been 

 excessive splitting of species in this genus. Many of the earlier 

 workers apparently assumed that every specimen from a new locality 

 represented a new species — giving little or no thought to the possibility 

 of widespread species. Others based their descriptions on tcneral or 

 badly mutilated specimens or overemphasized minor differences, real 

 or imaginary. The resulting confusion can be cleared away only by 

 a drastic synonymizing of names. 



The genus Pangaeus is readily divisible into two groups which the 

 author chooses to designate as subgenera. One occurs from Guatemala 

 northward and the other from Mexico southward. They are most 

 reliably separated by the shape of the mesopleural evaporatorium. 

 The southern subgenus, wliicli contains the tj^pe of the genus and 

 must be called Pangaeus, has the mesopleural evaporatorium extended 

 uninterruptedly into the posterolateral angle (fig. 103); while the 



