of the Pacific Shores of North America. 505 
thoracic segment. Abdomen subrectangular, broadest ante- 
riorly, nearly twice as long as broad, and equalling in length 
the four preceding thoracic segments taken together; its 
sides slightly concave ; posterior extremity with a deep con- 
cavity, terminating on either side in a sharp angular pro- 
jection or tooth. First and second segments of the abdo- 
men sufficiently well marked, the third also distinct on the 
sides :—the three occupying the anterior third of the length 
of the abdomen. Outer antenne reaching the fourth tho- 
racic segment; peduncle rather stout; flagellum 17-articu- 
late. Basal article of inner antenne greatly expanded, 
suborbieular. The opercular (first) pair of abdominal feet 
are broad, with the terminal joint square. Inner sides of 
ambulatory feet with short sete. Color greenish yellow, 
with a median line of dark-red. Length, 1.7; breadth, 0.33 
inch, Proportion of breadth to length, 1: 5.15. 
his species resembles the Mediterranean 4. hectica in 
seneral appearance, and is not liable to be confounded with 
any other species found on our western coast. 
The only specimen known was dredged in the Straits of 
DeF uca, opposite Fort Townsend, by Capt. Murden. 
Mus. Smithsonian. 
STENOSOMA GRACILLIMUM. Dana. 
Stenosoma gracillimum, Daxa ; Proc. Acad. Nat. Sci. Philad. 1854, vii. 175. 
Hab. California, (Le Conte.) 2 
Mus. of Prof. Dana. 
SPHERILLO AFFINIS, Dana. 
Spherillo affinis, Dana. Proc. Acad. Nat. Sci. Philad. 1854, vii. 176. 
A terrestrial species found in California by Dr. Le Conte. 
Mus. of Prof. Dana. 
JOURNAL B. S. N. H. 65 
