324 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



frontal process; flagellum about as long as the peduncle, and composed of 

 8-1 1 joints. Antennae reaching about to the postero-inferior angle of the 

 second thoracic segment; last 2 joints of the peduncle subequal; flagellum 

 longer than the peduncle and composed of 12-15 joints. 



Thoracic segments of subequal length, each crossed by a transverse ridge 

 which becomes fainter to obsolescence on the anterior segments; postero- 

 lateral angles of the segments produced backwards, those of the first 4 seg- 

 ments subacute, those of the last 3 becoming successively more rounded 

 posteriorly. Anterior segment of the pleon crossed anteriorly by a faint 

 line, and marked by 2 lines on either side which do not reach the middle of 

 the dorsal surface; a transverse, roughened line across the middle portion of 

 the segment. Caudal shield strongly convex, broadly rounded behind, rough- 

 ened with small granulations and marked with a double longitudinal row of 

 small tubercles which extend a little behind the middle of the dorsal surface ; 

 a transverse tubercle at the posterior end giving the segment, when viewed 

 laterally, the appearance of being turned up at the tip. Rami of the caudal 

 lamellae subequal, acute, and scarcely reaching beyond the tip of the caudal 

 shield; outer ramus armed with 4 or 5 sharp teeth (including the terminal 

 one) on the distal portion of the outer margin; inner ramus devoid of teeth 

 and fitting closely over the outer one. 



Color olivaceous. 



Length 9'mm. 



Found in marshy ground in San Francisco Bay, Cali- 

 fornia. 



This species is quite different from ^5*. oregonensis Dana; 

 the body is more convex, the head not so much set back 

 into the first thoracic segment, the caudal shield much 

 longer and much less flattened. In oregonensis the caudal 

 shield is perfectly smooth above and the outer ramus of the 

 uropods is devoid of teeth. In the character of the outer 

 uropods and several other features it resembles S. quadri- 

 dentatum Say of the Atlantic coast, but the thorax is nar- 

 rower, the epimera less distinct, the eyes larger and the 

 uropods shorter and more acute. 



University of Michigan, 



Ann Arbor, Michigan. 



