NO. 2134. NORTH AMERICAN COLLEMBOLOVS INSECTS— FOLSOM. 499 



3. Eyes eight on each side; lamella of mucro simple . .Pseudachorutes Tullberg, p. 500. 

 Eyes five on each side; lamella of mucro with oblique pocketlike lobes. 



Odontella Schiiffer, p. 502. 



4. Anal spines three; unguiculi and postantennal organs absent; fiu'cula short and 



weak; mucro hooked; eyes usually eight (sometimes five) on each side. 



Frieseu Dalla Torre, p. 499. 



Anal spines two; unguiculi and postantennal organs present; mucro lamellate; 



eyes five on each side XenyUodes Axelson. 



5. Postantennal organs present 6. 



Postantennal organs absent 7. 



6. Eyes five on each side or none; mouth parts not greatly reduced, not projecting 



in a cone; maxilla distally toothed Anunda I.aboulbene, p. 503. 



Eyes two or four on each side; mouth parts greatly reduced, projecting in a short 

 cone; maxilla stilettolike, untoothed Micranurida Borner. 



7. Eyes two or three on each side or none; mouth parts greatly reduced; projecting 



in a cone Paranura Axelson, p. 506. 



The genus Brachysius MacGillivray ('936, p. 317) is evidently syn- 

 onymous with PseudacJiorutes Tullberg. I have not seen specimens 

 of Brachysius dilatatus MacGillivray, the cotypes of which have been 

 misplaced, and in the absence of data in regard to the mucrones and 

 ungues can not place the species at present. 



Genus FRIESEA Dalla Torre. 



Triaena Tullberg, 1871. - . 



Fricsca Dalla Torre, 1895. 



Eyes 16. Postantennal organs absent. Antennae four-segmented. 

 Mandible without molar surface. Head of maxilla simple. Ungui- 

 culus absent. Furcula short, weakly developed; mucro hooklike. 

 Anal spines three. Anal segment small; supra-anal valve rounded, 

 semi-globose. Body without segmental tubercles. Cuticula tuber- 

 tuberculate. 



FRIESEA CALDARIA Guthrie. 



Plate 19, figs. 167, 168. 

 Friesia caldaria Guthrie, 1903. 



"Purplish blue above, paler beneath. Eye spots conspicuously 

 black. Body short and thick, with antennae, legs, and furcula to 

 correspond. Head triangular in outline as seen from the side. Claw 

 rather short and stout, tibiae with two clavate hairs nearly as long 

 as the claw. The fifth and sixth segments of the abdomen bear 

 dorsally several clavate hairs. The furcula is more rudimentary than 

 in any other genus, the manubrium being very short and broad, the 

 mucrones hooked at the end, and two-thirds as long as the dentes. 

 Dentes and mucrones together are but little longer than the larger 

 anal horns. The three anal horns (fig. 167) are situated in a triangle, 

 the hindmost one being median and somewhat smaller than the other 

 two. Each one is set on a short papilla (fig. 168). There is present 

 a well-developed tenaculum, with two-toothed blades much as in 



