448 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



slightly more thuii hiilf as long- as the upper margin, and the angle 

 between the lower margin and the palmar edge is less than 100°; 

 the notch at the distal end of the lower margin is longer than in 

 S. occidental e. 



''Abdominal shield is slightl}' longer than broad, otherwise as in 

 S. occidentale. 



" Uropoda seem to be only a little more than half as long as the 

 abdominal shield; the rami — preserved only in the young female — a 

 little shorter than in 6". occidentale. 



'•Length of the largest male 4.5 mm.'- — Hansen.'' 



Family XVII. JANIRID.E.'' 



Lateral parts of head lamellarly expanded. Eyes, when present, 

 usually subdorsal. First pair of antenna? sometimes well developed 

 with multi -articulate llagelkim, sometimes small with rudimentary 

 flagellum. Second antenniv generally with small scale outside of third 

 joint of peduncle; peduncle composed of six articles. 



First pair of legs sometimes prehensile, sometimes not differing from 

 the six following pairs, which are aml)ulatory; dactylus generally bi- 

 or tri-unguiculate. 



First pair of i)leopoda in female transformed into a single large oper- 

 cular plate, undivided; second pair wanting; outer lamelhe of two 

 succeeding pairs, third and fourth pleopoda, narrow and continent with 

 basal part; both branches well developed; hfth pair with only a single 

 branch. 



First pair of pleopoda in male coupled with the second pair and 

 forming a sort of compound operculum. The peduncles of the tirst 

 pleopoda are fused, are very long, with innnovable single branches. 

 Second pair with the distal joint of the peduncle situated outside of and 

 coupled with the hrst pair of pleopods; the 1)ranches are attached to 

 the inner mai'gin of the peduncle; the inner branch is geniculate, two- 

 jointed, the distal joint containing a cavity and being produced to a 

 point; the outer ])ranch is very short, two-jointed, and hook-shaped. 

 The third, fourth, and hfth pairs of pleopoda are similar to those of 

 female. 



ANALYTICAL KEY TO THE GENERA OF THE FAMILY' .lANIRID.E. 



a. Second pair of anteniue long, well (levt'lo[)e(l, with nuilti-articnlate flagellum; 



articles of peduncle not dilated. Mandil)les with cutting i)art composed of one 



or two serrated teeth. 



]i. First pair of antenn;e extremely small, with rudimentary flagellum, comjiosed 



of only two articles. Second pair of antenna' without a scale attached to the 



peduncle. Uropoda extremel.v small, branches short, nodiform. 



Geniii! J-xra Leach 



«Proc. Zool. Soc. London, 1905, II, Pt. 2, pp. 326-327. 



"See Hars for characters of family, Crust, of Norway, II, 1899, ]). 98, and Hansen, 

 l^oc. Zool. Soc. London, 1905, II, Pt. 2, pp. :;08-309, 315-316. 



