690 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



the seventh thoracic segment. The four following segments have the 

 lateral parts well developed. The sixth or terminal segment is rounded 

 posteriorly, with a slight emargination on either side of the rounded 

 median lobe for the reception of the basal articles of the uropoda. The 

 basal article of the uropoda has the inner distal angle produced so that 

 the inner side measures one and a half times longer than the outer side. 

 The inner branch of the uropoda is two and a half times longer than 

 the peduncle measured from the inner side; it terminates in two long 

 subequal hairs, which are a little less than one-fourth the length of the 

 inner branch. The outer branch is shorter than the inner branch, the 

 inner branch being a little less than one and a half times longer than 

 the outer branch. The outer branch is also tipped with two short hairs. 



All the legs are ambulatory. 



In color it is a reddish brown, mottled with yellow, and with two 

 longitudinal rows of yellow spots, one on either side of the body about 

 the place where the epimera are united with the segments. 



LIGIDIUM GRACILIS (Dana). 



Styloniscus gracilis DANA, Proc. Acad. Nat. Sci. Phila., VII, 1854-55, p. 176. 

 STIMPSON, Bost, Jour. Nat. Hist, VI, 1857, p. 506. 



Alloniscus maculosus HARFORD, Proc. Cal. Acad. Sci., VII, 1877, p. 54. 



Styloniscus gracilis BUDDE-LUND, Crust. Isop. Terrestria, 1885, p. 271. UNDER- 

 WOOD, Bull. 111. State Lab. Nat. Hist., II, 1886, p. 364. RICHARDSON, Proc. 

 U. S. Nat. Mus., XXI, 1899, p. 867; Ann. Mag. Nat. Hist. (7), IV, 1899, p. 

 335; American Naturalist, XXXIV, 1900> p. 306. HOLMES, Proc. Cal. Acad. 

 Sci. (3), III, 1904, pp. 318-319. 



Locality. California. 



' ' Thoracic segments smooth, glossy, and of subequal length ; postero- 

 lateral and antero-lateral angles of the first four rounded, the postero- 

 lateral angles of the last three segments acute and produced backward. 



"Abdomen longer than wide, abruptly narrower than the thorax, 

 the first two segments shorter than the others, the three following 

 segments with the postero-lateral angles acute and produced backward. 

 Terminal segment twice as wide as long and very broadly rounded. 



"Head transverse, devoid of prominences, front broadly rounded. 

 Eyes rather large, reaching the lateral margins of the head. Anten- 

 nules three-jointed, not exceeding the second basal joint of the antennae; 

 first joint broad, distally widened; second joint subcylindrical, slightly 

 longer and much narrower than the first; third joint very minute and 

 joined to one corner of the preceding. Antennae nearly one-half the 

 length of the body, first joint short, transverse, second and third joints 

 oblong, cylindrical, subequal, fourth joint as long as the three preced- 

 ing, fifth joint narrower and slightly longer than the fourth; flagellum 

 about as long as the two preceding joints and composed of thirteen to 

 fifteen articulations. 



"Mandibles short and ve^ stout, having a large molar tubercle and 



