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 size. 

 They are large, very much expanded, rounded posteriorly, 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 tubercles at the base of the terminal segment. Several 

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



Both sexes are known, the male and female being 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. 

 3204. ' 



DYNAMENE GLABRA Richardson. 



Dynamene glabra RICHARDSON, Proc. U. S. Nat. Mus., XXI, 1899, p. 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; e} 7 es situated post-laterally. First 

 pair of antennae extend to the eye; first joint oblong; 

 second joint short, half as long as 

 first; flagellum consists of six arti- 

 cles. Second pair of antennae ex- 

 tend to the posterior margin of the 

 first thoracic segment; flagellum 

 consists of about ten articles. 



The thoracic segments are subequal; the first is a 

 little longer than any of the others. 



The penultimate 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 

 P art ^ **" s segment is quite 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 large 

 and rounded posteriorly; the outer 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. ABDOMEN 

 AND LAST TWO THO- 

 RACIC SEGMENTS. 



Xl3}. 



FIG. 322. DYNAMENE 

 GLABRA. SECOND 

 PLEOPOD OF MALE. 

 x 51|. 



