178 
PACIFIC SCIENCE, Vol. VII, April, 1953 
It is difficult to recognize the species of 
terrestrial isopods based only upon females, 
but, I think that Oregoniscus nearcticus (Arc- 
angeli) and Caucasonethes rothi n. sp. are dis- 
tinct. They differ in many points: 
(1) The size is very different: 0. nearcticus, 
2.73 mm. long; C. rothi, 5.5 mm. long. 
(2) The number and disposition of sensory 
hairs {aesthetascs) of antennula is very 
different in the two species. 
(3) Antennae very long in C. rothi, short in 
0. nearcticus "caratteristica e la incava- 
tura che dorsalmente presenta nelle 
meta distale esterna il 5° articolo dello 
scapo” (Arcangeli, 1932). This charac- 
ter is missing in C. rothi. The flagellum 
of the antenna is six-segmented in C. 
rothi, four-segmented in 0. nearcticus. 
(4) The legs of C. rothi are long and slend- 
er, whereas in 0 . nearcticus "e da notarsi 
la larghezza e relativamente piccola 
lunghezza specialmente del meropodi- 
te, carpopedite, e propodite, che con- 
feriscono al membro un aspetto mas- 
siccio” (loc. cit.). 
(5) In C. rothi the endopodite of the uro- 
pod is only a little shorter (about one 
tenth) than the exopodite. In 0. nearc- 
ticus, the endopodite is about one half 
as long as the exopodite. 
REFERENCES 
Arcangeli, A. 1932. Isopodi terrestri raccolti 
dal Prof. Silvestri nel Nord- Am erica. Por- 
tici R. Scuola Super, di Agr., Lab. Zool. Gen. 
e Agr., Bo/. 26: 121-141, 7 figs. 
Birstein, J. a. 1950. The Fauna of the west- 
ern Transcaucasus caves. Zoologitchesky Jour. 
29: 354-366. 
Hatch, M. H. 1947. The Chelifera and Iso- 
poda of Washington and adjacent regions. 
Wash, [state] Univ., Pubs. Biol. 10: 155-274, 
18 pis. 
Vandel, a. 1950. Isopodes terrestres recueil- 
lis par C. Bolivar et R. Jeannel (1928) et le 
Dr. Henrot (1946). Arch, de Zool. Expt. et 
Gen. 87: 183-210, 20 figs. 
Verhoeff, K. W. 1932. Cavernicole Onis- 
coideen. 44. Isopoden-Aufsatz. Hohlen-u, 
Karstf. Berlin, Mitt. 1932: 3-15, 21 figs. 
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