600 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



One specimen was collected by Dr. L. Stejneger at El Yunque, 

 Porto Rico, at an altitude of 2,800 feet. 

 Type. Cat. No. 23912, U.S.N.M. 



1O6. Genus ONISCUS Linnaeus. 



Body broad, depressed, very little or scarcely contractile. Surface 

 of body granulated or tuberculate. Head with well-defined lateral 

 lobes; front marginate, not produced in the middle. Abdomen not 

 abruptly narrower than thorax; third, fourth, and fifth segments with 

 epimera large, acute, and produced backward. Terminal segment 

 greatly produced. Eyes large, lateral. Second pair of antennae long; 

 flagellum composed of three articles. 



Opercular plates of the pleopoda without tracheae. 



Uropoda produced, with the inner branch inserted far in front of 

 the outer, near the inner antero-lateral angle of the peduncle. 



Lateral parts of the thoracic segments expanded; posterior angles 

 of all the epimera acute. 



ONISCUS ASELLUS Linnaeus. 



Oniscus asellus LINNAEUS, Fauna Suecica, 2d ed., 1761, p. 500. 



Oniscus murarius CUVIER, Jour. Hist. Nat., II, 1792, p. 23, pi. xxvi, figs. 11-13. 



Oniscus affinis SAY, Journ. Acad. Nat. Sci. Phil., I, 1818, pp. 430-431. 



Oniscus vicarius STUXBERG, Ofvers. Svenska Vet. Akad., Forh., 1872, Pt. 9, p. 3; 

 1875, Pt. 2, p. 50. 



Oniscus asellus BUDDE-LUND, Crust. Isop. Terrestria, 1885, pp. 202-204. 



Oniscus affinis UNDERWOOD, Bull. 111. State Lab. Nat Hist., II, 1886, p. 361. 



Oniscus vicarius UNDERWOOD, Bull. 111. State Lab. Nat. Hist., II, 1886, p. 361. 



Oniscus. asellus SARS, Crust. Norway, II, 1899, pp. 171-172. RICHARDSON, Ameri- 

 can Naturalist, XXXIV, 1900, p. 305; Proc. U. S. Nat. Mus., XXIII, 1901. 

 pp. 562-563. 



Oniscus affinis RICHARDSON, American Naturalist, XXXIV, 1900, p. 305; Proc. 

 U. S. Nat. Mus., XXIII, 1901, p. 563. 



Oniscus asellus STOLLER, 54th report New York State Museum, 1902, p. 213. 

 PAULMIER, Bull. New York State Museum, 1905, pp. 180-181. 



Localities. Greenland; North America, at Woods Hole, Massachu- 

 setts; Salem, and Beverly, Massachusetts; New York City; Schenec- 

 tady, New York; Rock Island, Illinois; Providence, Rhode Island; 

 Syracuse, New York; Freeport, Maine; Pennsylvania; also Sweden; 

 Denmark; Germany; Newfoundland; Canada, near Niagara; Holland; 

 Great Britain; France; Spain; Italy; Azores; Iceland; coast of Nor- 

 way; "Ashensee Tyrol " 950 meters alt. (Dr. Stejneger). 



Found under dead logs, dead leaves, and stones; common in hot- 

 houses. 



Specimens identified by Dr. Joseph Leidy as Oniscus affinis Say 

 and sent to me by Doctor Calvert of the University of Pennsylvania, 



See Budde-Lund for characters of genus, Crustacea Isopoda Terrestria, 1885, 

 p. 202, and Sars, Crustacea of Norway, II, 1899, pp. 170-171. 



