90 FOLSOM [92] 



second pair of lateral teeth is found one-seventh from the apex, and a 

 fifth, or median, tooth is situated as far again from the apex ; inferior 

 claws untoothed, slender, gradually attenuating into a filament which 

 extends beyond the superior claw, inner margin roundly and narrowly 

 dilated at base ; both claws are basally tuberculate. Anal spines (figs. 

 35, 36) two, less than half as long as a superior claw, almost straight, 

 separated basally by half their length and not seated upon papillae. 

 Clothing of short dense curving setae with occasional long stiff setae on 

 antennae and abdomen, the latter more numerous towards the apex of 

 the abdomen. Maximum length, 4 mm. 



Type. Cat. No. 5436, U. S. Nat. Museum. 



Sixteen types : ten from Seldovia, Cook Inlet, July, 1899, under 

 stones at tide mark (No. 62) ; five, Cook Inlet, 1899 (No. 60) ; one 

 from St. Paul Island, Bering Sea, August i, 1897. 



Although A. dentata shares many of its characters with other spe- 

 cies, in no other form do they approach a similar combination. The 

 five-toothed claws are most distinctive. 



ISOTOMA FIMETARIA (L.) Tull. 



(PI. vii, figs. 37-39.) 



? Podura terrestris alba LINNAEUS, Fauna Suecica, Ed. I, p. 343, 1746. 



f Podura fimetaria LINNAEUS, Fauna Suecica, Ed. 2, 1761. 



Isotoma alba TULLBERG, Ofv. k. vet. Akad. forh., xxvm, no. i, p. 152, 1871 

 (Sweden). 



Isotoma fimetaria TULLBERG, k. sven. vet. Akad. hand., x, no. 10, p. 48, 

 taf. 9, figs. 32, 33, 1872 (Sweden). TULLBERG, Ofv. k. vet. Akad. forh., 

 XXXlll, no. 5, p. 37, 1876 (Greenland, Siberia). MAcGlLLlVRAY, Can. 

 Ent., xxill, p. 273, 1891. UZEL, Sitzber. k. boh. Gesell. Wiss., II, p. 66, 

 1891 (Bohemia). SCHOTT, K. sven. vet. Akad. hand., xxv, no. n, p. 75, 

 1894 (Siberia). DALLA TORRE, Die Gattungen und Arten der Apterygo- 

 genea (Brauer), p. 9, 1895. REUTER, Acta Soc. Faun. Flora fenn., xi, 

 no. 4, pp. 28-29, 1895 (Finland). MACGILLIVRAY, Can. Ent., xxvin, 

 p. 58, 1896. SCHAFFER, Mitt, naturh. Mus. Hamburg, xin, p. 183, 



1896 (Germany). SCHOTT, Proc. Cal. Acad. Sc., vi (2), p. 184, 1896 

 (California). LIE-PETTERSEN, Bergens Mus. Aarb. (1896), no. 8, p. 18, 



1897 (Norway). MEINERT, Vidensk. Med. naturh. Foren. Kjobenhavn 

 (1896), p. 169, 1897 (Greenland). LIE-PETTERSEN, Bergens Mus. 

 Aarb., no. 6, p. 13, 1898 (Norway). SCHERBAKOF, Zool. Anz., xxi, p. 

 58, 1898 (Russia). SCHERBAKOF, Materiali, etc., Apteryg., Vicinity 

 of Kief, p. 12, 1898 (Russia). CARPENTER and EVANS, Proc. R. Phys. 

 Soc. Edinburgh, xiv, p. 251, pi. 8, figs. 3, 4, 1899 (Scotland). SCHER- 

 BAKOF, Zool. Anz., xxn, p. 47, 1899 (Spitzbergen). CARPENTER, Sc. 

 Proc. R. Dublin Soc., IX. (n. s.), pt. 3, p. 274, 1900 (Franz Josef Land). 

 SCHAFFER, Fauna Arctica, i, lief. 2, p. 247 (Massachusetts). 



White. Eyes absent. Postantennal organs small, elliptical. An- 

 tennae (fig. 37) subequal to head in length, segments related as 3 : 5 : 



