686 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



124. Genus LIGIDIUM Brandt." 



Body obloiio-; Htteiuuited l^ehind. 



First pair of antennt« projecting in front; terminal joint small, artic- 

 ulated at one angle of middle joint. Mandibles without ciliated lappet 

 behind cutting part. Palp of maxillipeds with articles not much 

 expanded; epignath narrow, linguiform. 



Abdomen abruptly narrower than thorax; terminal segment with 

 the lateral parts not developed. 



Uropoda with the peduncle produced at the inner post-lateral angle 

 in a conical process, to which the inner branch is articulated. Branches 

 unecjual in length; inner branch provided with two long and slender 

 terminal bristles.^ 



ANALYTICAL KEY TO THE SPECIE8 OF THE GENTS LIGIDIUM. 



(I. Inner branch of the uropoda furnished with two long apical t)ristle8. 



/*. Inner branch of the uropoda not extending to the tip of the outer branch. 



Ligidium Jujpiiorinn (Cuvier) 

 6'. Inner branch of the uropoda longer than the outer branch and surpassing it. 

 c. Inner process of the basal article of the uropoda one-fourth as long as the 

 outer branch. Inner branch one-sixth part longer than the outer branch; 

 terminal filaments equal to half the length of the outer branch. 



Ligidium tenue Budde-Lund 



c\ Inner process of the basal article of the uropoda six or seven times shorter than 



the outer branch. Inner branch one-third part longer than the outer 



branch. Terminal bristles equal to one-third the outer l)ranch in length. 



Ligidium longic.au dahuii Stoller 



a' . Inner Ijranch of the uropoda not furnished with apical bristles, but tipped with 



setse Ijigidium gracilis (Dana) 



LIGIDIUM HYPNORUM (Cuvier). 



Omscus hypnorum Cuyier, Jour. d'Hist. Nat., II, 1792, p. 19, pi. xxvi. 



Ligidium hypnorum Budde-Lunu, Naturh. Tidsskrift (3), VII, 1870, p. 225. — 

 Stuxberg, Ofversigt Vetensk. Akad. Forhandl., 1875, No. 2, p. 48. — Budde- 

 Lund, Crust. Isop. Terrestria, 1885, pp. 254-256. — Underwood, Bull. 111. 

 State Lab. Nat. Hist., II, 1886, p. 361.— 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. 



Localities. — California; Niagara in Canada; also Sweden, Den- 

 mark, Germany, France, and the British Isles; Constantinople and 

 • ' Chersoneso Taurico " (Budde-Lund). Found in moist places. Budde- 

 Lund thinks that the species found in North America and recorded by 

 Stuxberg as the above is not likely the same, or rather he douljts that 

 tliis species occurs in North America. I have never seen any speci- 

 mens of this species. 



ft From the description and figures which Prof. S. J. Holmes gives of Styloniscus 

 gracilis Dana, the species ought to be referred to the genus Ligidium Brandt. The 

 genus LJuphiloscia Packard is probably a synonym of Ligidiu))i. 



'^See Sars for characters of genus. Crust, of Norway, II, 1899, p. 157, and lUidde- 

 Lund, Crustacea Isopoda Terrestria, 1885. 



