﻿236 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 102 



Platyrrhacidae (Lief. 69, p. 202), the latter being represented in his 

 arrangement by the single genus Platyrhacus. Seven other genera of 

 Attems' "Platyrrhacidae" have the characters of the Eiiryuridae as 

 here understood.^ Since the appearance of Attems' work, Chamberlin 

 has described a number of species and genera from northeastern Peru 

 (1941, Bull. Amer. Mus. Nat. Hist., pp. 498 et seq.). 



I wish to express my indebtedness to Dr. E. A. Chapin, curator, 

 division of insects, United States National Museum, who has greatly 

 facilitated my work at that institution ; to R. L. Wenzel, division of 

 insects, Chicago Natural History Museum, for the loan of many 

 specimens from collections under his charge; and to Dr. Clarence J. 

 Goodnight, department of biological sciences, Purdue University, who 

 has kindly given me valuable material from his Central American 

 collecting. 



REMARKS ON TAXONOMIC CHARACTERS 



Attems' key to the five American genera recognized by him is based 

 to a considerable extent upon sculpture of the dorsum. Euryurus and 

 Pycnotropis are separated off in couplet 4 by the statement "Metazoni- 

 ten glatt oder nur mit Spuren einer polygonalen Felder," as opposed 

 to "Metazoniten mit Querreihen grosser Tuberkeln," which leads to 

 Polylepiscus and AmpUnus. 



This reliance upon tergite modification leads to considerable diffi- 

 culty. Even in the four genera mentioned, one finds smooth species 

 in "tuberculate" genera, and vice versa. The issue is complicated by 

 the addition of Chamberlin's four Peruvian genera and one from 

 Panama to be described herein. There seems to be such variability in 

 the development of polygonal areas on the dorsum that its practical 

 value is largely negated. The new Panamanian form keys out to 

 Pyc7iotropis, and the gonopods are of the type found in that genus, but 

 other characters are those of Phinotropis (Polylepiscus, in part, of 

 Attems). Because of the difficulty attendant upon the use of sculp- 

 ture, I believe it advisable to appeal to other characters, such as sub- 

 antennal swellings, anal sternite, and male gonopods, for generic 

 diagnosis. 



The following key appears to be satisfactory at present for the rec- 

 ognition of American genera : 



* The genus Aphelidesmus has been placed in the Euryuridae by recent American worlters 

 at one time or another, since the time of Coolc (1895) and Pocock (1909). Despite its 

 somewhat truncate terminal segment, Aphelidesmus properly belongs in the family 

 Strongylosomidae, a group with somewhat distant a£Snities. 



