516 PROCEEDINGS OF THE NATIONAL MUSEUM vol. in 



The only nymphal material available was of the common North 

 American species ciliatus (mirabilis auct., nee Perty). The several 

 specimens involved possessed the submarginal setae on the head, 

 the longer, finer spines on the posteroventral margin of the posterior 

 tibia and the simple second labial segment. 



Type of genus. — Cyrtoinenus castaneus Amyot and Serville (1843, 

 p. 91), subsequently designated by Kirkaldy (1903, p. 230) ; of Syllabus, 

 Cyrtomenus emarginatus StM (1862, p. 95), monobasic. C. castaneus 

 belongs to the common Cyrtomenus of the southern United States and 

 therefore must fall as a synonym of Palisot de Beauvois' name ciliatus, 

 which antedates it by 38 years. 



Distribution. — This genus is known to occur only in the Western 

 Hemisphere where its included species range from lat. 40° N. in the 

 eastern United States south and west through Central America to 

 about lat. 35° S. in Argentina in South America. 



Discussion. — StS^l's species Cyrtomenus emarginatus, for which 

 Signoret (1879, p. clxxiii) erected the new genus Syllabus, is here being 

 returned to its original assignment to Cyrtomenus. This is being done 

 because emarginatus shows the same thick-set, convex form, the 

 flattened and somewhat curved posterior tibia with the longer, more 

 slender posteroventral spines, the short osteolar peritreme with a 

 posterior, subapical hook but no differentiated terminal process, and 

 the indicated closer relationship with teter whose placement in Cyrto- 

 menus has been generally accepted. Signoret apparently based his 

 separation of the two genera chiefly on the triangularly produced 

 apices of the juga. While this is admittedly a conspicuous character 

 in a family of superficially morphologically similar forms, it is hardly 

 of sufficient fundamental value to outweigh the several features which 

 ally emarginatus to Cyrtomenus. 



The species included in this genus as thus understood may easily be 

 arranged in two major groups on the basis of the shape of the meso- 

 pleural evaporatorium. In one group, which contains emarginatu<i 

 and the other larger South American species, this evaporatorium i 

 interrupted posteriorly by a submarginal, mesally directed spur from 

 the lateral area which reaches more than half way to medial angle os 

 segment; in the other group the mesopleural evaporatorium is noft 

 interrupted (fig. 109) by such a shining area. If these two groups are 

 recognized as subgenera, as is proposed to be done here, the one with 

 the uninterrupted mesopleural evaporatorium contains the genotype, 

 castaneus, and will take the subgeneric name Cyrtomenus, while the 

 other will take the name Syllabus which had previously been proposed 

 for one of its included species, emarginatus. 



