NO. 2134. NORTH AMERICAN COLLEMBOLOUS INSECTS— FOLSOM. 479 



developed subapical many-toothed molar surface. Unguiculus pres- 

 ent (except in subgenus ScJwtteUa). Clavate tenent hairs present in 

 most species. Furcula and tenaculum present. Anal spines pres- 

 ent (except in some species of ScJidttcUa), usually two. Integument 

 tuberculate. 



The genus Ilyyogastrura Bourlct, revived by Bonier ('06, p. 156) 

 and adopted by some writers, is invalid. In 1839 Bourlct made 

 the genus Ilypogastrura to receive a single species, Podura aquatica 

 Linnaeus, In 1842 he used the same name in a new sense for species 

 of Acliorutes. Ilypogastrura is a homonym, and the tyi^ie of Ilypo- 

 gastrura is not Achorutes muroruin but Podura aquatica Linnaeus. 



KEY TO SPECIES OP ACHORUTES. 



1. Dentes with several or many large dorsal teeth; color dark bhie 2. 



Dentes without dorsal teeth 3. 



2. Anal spines minute socialis, p. 484. 



Anal spines long harvcyi, p. 486. 



3. One long tenent hair, usually but not always clavate 4. 



Two or three long clavate tenent hairs 12. 



4. Anal spines present 5. 



Anal spines absent; yellow mottled with brown tigrina, p. 480. 



5. Body with stout capitate hairs; color dark blue packardi, p. 482. 



Body without capitate hairs 6. 



6. Anal spines long, at least three-quarters as long as hind ungues 7. 



Anal spines short, one-third to one-half as long as hind ungues 10. 



7. Outer lamella of mucro with a large subtriangidar lobe (fig. Ill) 8. 



Outer lamella of mucro with a small subtriangular lobe (fig. 92) or with entire 



margin 9. 



8. Anal spines long; at least as long as the hind ungues; lobe of outer lamella not 



thickened distally; antennae with a large eversible sac between the third and 



fourth segments armatus, p. 491. 



Anal spines three-quarters as long as hind ungues; lobe of outer lamella ter- 

 minating distally in a large tooth-like thickening; no eversible antennal 

 sac pscudarmatus, p. 490. 



9. Outer lamella of mucro with a small subtriangular lobe; anal spines equal to, 



or longer than, hind ungues guthrici, p. 489. 



Outer lamella of mucro with entire dorsal margin; anal spines three-quarters as 

 long as hind ungues packardi, var. dcntatus, p. 483. 



10. Anal spines one-half as long as hind ungues; mucro not hooked apically; dark 



blue copiosus, p. 480. 



Anal spines less than one-half as long as hind ungues; mucro hooked apically. .11. 



11. Color dark blue maturus, p. 481. 



Cream yellow, marked with pale purple brcvispinus, p. 482. 



12. Outer lamella of mucro large (fig. 86); ventral margin of mucro rounded dis- 



tally •- . viaticus, p. 489. 



Outer lamella small, narrow; ventral margin of mucro almost straight 13. 



13. Anal spines minute, less than one-fourth as long as hind ungues 



viacgillivrayi, p. 488. 

 Anal spines one- third to one-half as long as liind ungues 14. 



14. Mucro with upturned apex. tullbergi, p. 487. 



Mucro straight apically humi, p. 487. 



