AKT. 17 ON" TEEEESTEIAL ISOPODS LOHMAFDEE 6 



of all the terrestrial Isopods in the Scandinavian countries. It is 

 remarkable that the males of this species are usually much rarer 

 than the females. Only in southern France do males and females 

 appear in about equal numbers. In central France males are more 

 uncommon and in the northern part very rare. (See Vandel, 1923, 

 p. 793.) In the south of Sweden I have, on an average, found only 

 1 male to each 100-200 females. In northern Europe, consequently, 

 parthenogenesis seems to be the general rule and the uncommon males 

 can be of no great importance in the perpetuation of the species. It 

 would be of interest to learn the corresponding facts for the tribe of 

 Trichoniscws piosillus inhabiting North America. 



Whether the North American Trichoniscus pusillus is identical 

 with the true TricKoniscus yusillus Brandt of west and north Europe 

 can be made certain only after the discovery of a male, as com- 

 parison of females alone can not decide this point. 



TRICHONISCUS PYGMAEUS Sars, 1899 



Locality. — On lily bulbs from Scotland, intercepted at New York 

 City, October 4, 1923, I. Schiller, collector. 



Remarks. — This species is not rare in southern Sweden, but occurs 

 only synanthropically in hothouses, gardens, and graveyards, and in 

 Norway, Germany, and England it is found in similar locations. It 

 will, on closer investigation, certainly be found, at least in hothouses, 

 in the eastern parts of North America. Because of its concealed 

 habitation, usually down in the earth, under stones, rotten wood, etc., 

 it is difficult to discover. Like other species of Trichoniscidae, it is 

 most easily collected during the early spring and the late autumn. 

 The males of this species are almost as common as the females. 



HAPLOPHTHALMUS DANICUS Budde-Lund. 1879 



1899 Haplophthalmns puteus Hay, Proc. U. S. Nat. Mus., vol. 21, p. 871, 



pi. 86, figs. 1-15. 

 1905 Haplophthalmus puteus Richardson, Bull. U. S. Nat. Mus., No. 54, 



p. 697, fig. 739. 



Localities. — Plummer Island, Potomac River, Maryland, from deep 

 layer of old leaves. May 6, 1924, H. S. Barber, collector. From soil 

 about roots of asparagus from Germany, intercepted at Philadelphia, 

 Pennsylvania, November 4, 1924, R. S. Cogswell, collector. 



In 1899, Hay described a terrestrial Isopod from wells in Indiana 

 as new to science, under the name of HapIophtJiahnus puteus. Ver- 

 hoeff later (1908, p. 189) demonstrated that this species was certainly 

 identical with LI. danicus Budde-Lund which is widely distributed 

 in Europe. Verhoeff points out that there is only a single character 

 that distinguishes one species from the other, namely, the shape of 

 the telson, but accentuates at the same time that this difference is 

 probably not real but caused by an error of observation by Hay. 



