AET. 6 TROPICAL AMEEICAN APTERYGOTA FOLSOM 5 



Accessory body (" Nebenkorper ") absent. Antennae three-fourths 

 as long as the head ; segments as 10 : 10 : 13 : 13 ; third and fourth 

 segments demarcated by a suture ventrally but not dorsally. Sense 

 organ of third antennal segment (fig. 32) consisting of a single peg, 

 resembling a short stout seta, with four accompanying setae. Fourth 

 segment with a terminal sense organ (fig. 33) composed of three 

 eversible vesicles; also with several distal curving slender olfactory 

 setae, but l.ttle different from ordinary setae. Unguis (fig. 34) stout, 

 curving; inner margin with a minute tooth one-third from the base 

 on fore and mid claws, the tooth obscure or absent on hind claws ; a 

 pair of minute slender lateral teeth, one-third from the base, occurs 

 on the first and second pairs of ungues, but is often obscure or absent 

 on the third pair. Unguiculus absent. Tenent hairs absent. Anal 

 spines absent; anal lobes rounded. Furcula extending as far as the 

 ventral tube. Dentes (fig. 35) stout, with a few dorsal tubercles 

 somewhat larger than those of the cuticula in general, and with 5 

 dorsal setae. Mucrones (figs. 35-37) two-fifths as long as dentes, 

 bilamellate; outer lamella wider and more rounded than the inner 

 lamella, with margin either entire or roughened ; both lamellae end- 

 ing before the apex of the mucro, which is rounded and not upturned. 

 Rami of tenaculum tridentate; corpus without setae. Body setae 

 (fig. 38) stout, slightly curving, of two sizes — large and small — ^both 

 k-nds distally, and mostly unilaterally, serrate. Length, 0.8 mm., 

 occasionally 1 mm. 



The number of tubercles in the postantennal organ was as follows, 

 in eighteen specimens : 



Right Left Right Left 



6 6 5 6 



5 6 6 8 

 ? 4 5 6 



6 5 6 

 6 5 6 6 

 6 7 6 5 



6 7 7 6 



7 6 6 7 

 7 7 7 3 



The types were selected from a large number of specimens, taken 

 in limestone caves in bat dung, in company with two other species 

 described in this paper. 



Headwaters of Chilibrillo River, Canal Zone, September 29, 1923, 

 J. Zetek and I. Molino, collectors. 



Syntypes.—C2it. No. 40382, U.S.N.M. 



