ISOPODS OF NORTH AMERICA. 



301 



longation of the lateral margins, which prolongations meet anteriorly 

 and are divergent posteriorly, so that a triangular excavation is 

 formed on the posterior end of the segment immediately below the 

 heart-shaped opening. 



The two branches of the uropoda are similar in shape and sij5e. 

 Thev Hre large, very much expanded, rounded ])()stei-iorly, with mar- 

 gins distinctly crenulate or denticulate, and extend some distance 

 beyond the tip of the terminal abdominal segment. 



The color is brown, with markings of black. Surface smooth, with 

 the exception of the abdomen, which is very granular. 



Several specimens differ from the specimen described in not having 

 the seventh thoracic segment produced in lobes, and are without the 

 four small tul)ercles at the base of the terminal segment. Several 

 differ in having the uropoda not longer than (lie terminal segment. 



Both sexes are known, the male and female l)eing alike in every respect; 

 in the male the inner branch of the second pleopods carries a stylet. 



Cotypes are in the Peabody Museum. Yale University. Cat. No. 

 32U4. 



DYNAMENE GLABRA Richardson. 



Dynamem glabra Richardson, Proc. U. S. Nat. Miis., XXI, 1899, j). 834; Ann. 

 Mag. Nat. Hist. (7), IV, 1899, p. 178; American Naturalist, XXXIV, 1900, 

 p. 224.— Holmes, Proc. Cal. Acad. Sci. (3), III, 1904, No. 11, p. .304. 



Localities. — Monterey Bay, California; Mendocino 

 County, California; San Diego, California, 

 Body oval; surface smooth. 



Head small; eyes situated post-laterally. First 

 pair of antenna? extend to the eye; first joint oblong: 

 second joint short, half as long as 

 first; tlagellum consists of six arti- 

 cles. Second pair of antenna? ex- 

 tend to the posterior margin of the 

 first thoracic segment; fiagellum 

 consists of about ten articles. 



The thoracic segments arc sube(|ua 

 little longer than any of the others. 



The penidtimate abdominal segment consists of 

 several coalesced segments, as indicated by the suture 

 lines. The terminal segment is triangular, with a 

 small median excavation at its extremity. The lower 

 part of this segment is (piite flat, the slope being 

 gradual from the convex upper part or base of the 

 segment to the extremity. The surface is perfectly 

 smooth. ■ The inner branch of the uropoda is larg(^ 

 and rounded posteriorly; the out(>r branch is small, though similar in 

 shape, and is much shorter than the inner branch. 



A number of specimens were collected by Mr. Heath at Monterey 

 Bay, California, at the surface. 



Fig. 321.— Dynamene 

 glabra. .\bdomen 

 and last two tho- 

 racic segments. 



Xl3 i. 



d: the first is a 



Fig. 322.— Dynamene 

 GLABRA. Second 



PLEOPOD OF MALE. 



X h\\. 



