114 PROCEEDINGS OF THE NATIONAL MUSEUM vol. m 



tholid, it almost certainly wiU be necessary to recognize an additional 

 subfamily for Cyclothyrophorus. 



Messicobolus Brolemann, 1914, p. 32. 



Type species: Spirobolus godmani Pocock, by original designation. 



This genus of large robust spiroboloids has been referred to the 

 Atopetholidae in recent papers by R. V. Chamberhn, but the good 

 figures of the gonopods published by Carl indicate clearly that Messi- 

 cobolus and the possibly synonymous Oxobolus constitute a distinct 

 taxonomic group well differentiated from other presently recognized 

 spiroboloid families. 



Atopetholid Genera of Uncertain Position 



The following generic names appear to be based on species of the 

 Atopetholidae, but are so poorly described that it is impossible to 

 refer them to a subfamil}^ with anj^ degree of confidence. 



Hesperolus Chamberlin, 1918, p. 170. 



Type species: Hesperolus wheeleri Chamberlin, by original designa- 

 tion. 



The original description of H. wheeleri included no illustrations, and 

 it is difficult to visualize the gonopodal structure from the description. 

 The tiny species was collected in the Santa Ynez Mountains near 

 Santa Barbara, California, and it is hoped that topot3^pes can eventu- 

 ally be obtained and studied for a correct placement of the genus. 



Tidolus Chamberlin, 1949, p. 169. 



Type species: Atopetholus parvus Chamberlin, by original designa- 

 tion. 



The type species was described as an Atopetholus, and the diagnosis 

 of Tidolus is largely a comparison with that genus. Here again, 

 however, the type species is not illustrated, and the brief description 

 of its gonopods is not sufficient to provide a good idea of their form. 

 Since parvus was collected at Claremont, California, it should not be 

 difficult for some collector to eventually secure topotypical specimens. 



Family Atopetholidae Chamberlin 



Atopetholidae Chamberlin, 1918, p. 167; 1949, p. 168.— Chamberlin and Hofifman, 



1958, p. 152. 

 Onychelidae Verhoeff, 1938, p. 273. 



Small to medium sized spiroboloids, characterized by the structure 

 of the male gonopods. The anterior pair consists of a transverse or 

 moderately arched sternite, with the usual sternal apodemes; coxae 

 of normal configuration, separated by a median thickening of the 



