742 CRUSTACEA. 



gellum, more enlarged ; /, extremity of flagellum, ibid. ; g, tarsus of 

 sixth or seventh pair of legs; h, outline of eye, in lateral view. 



Length, twelve lines, exclusive of caudal stylets. Base of stylets 

 as long as breadth of last abdominal segment ; the branches equal, 

 slender, with an oblique seta at apex of the inner. Joints of flagellum 

 mostly having their length more than twice their breadth, twenty- 

 seven to thirty-two in number, the spinules few, exceedingly short, 

 not one-fourth the diameter of the joints in length; terminal joints 

 appear scabrous under a high magnifying power. The last segment 

 has the posterior angles prominent and acute ; and a short distance 

 inside of the angles, the posterior margin has a crenature with an 

 angle either side, while the middle of the margin is low triangular 

 and subacute. Surface of thoraoic segments very nearly smooth. 



LYGIA OCCIDENT ALIS. 



L. Gaudichaudii affinis. Segmenta thoracis plane sed minute granulata. 

 Antennas tJiorace non longiores, flagello lQ-lS-articulato, articulis 

 versus basin latitudine raro duplo longioribus, spinulis subtilissimis, 

 paucis. Styli caudales fere dimidii corporis longitudine, basi latitur 

 dinem segmenti ultimi vix asquante, ramis acquis, interno seta obliqud 

 confecto. 



Near the Gaudichaudii. Segments of thorax distinctly though mi- 

 nutely granulate. Antennae not longer than thorax ; flagellum six- 

 teen to eigh teen-jointed ; joints towards basal portion rarely twice as 

 long as broad; spinules very minute and few. Caudal stylets not 

 half as long as body ; base shorter than breadth of last abdominal 

 segment ; branches equal, the inner with an oblique seta at apex. • 



Plate 49, fig. 7 a, abdomen, enlarged ; b, part of base of antennae ; 

 c, basal part of flagellum ; d, extremity of flagellum ; e, tarsus of sixth 

 or seventh pair of legs. 



Near Sacramento River, California. — C. Pickering. 



Length, exclusive of caudal stylets, one inch. The eyes are large 



