178 Miss H. Richardson on the Isopods of the 



24. Dynamene glabra^ sp. n. 



Body oval ; surface smooth. 



Head small ; eyes situated post-laterally. First pair of 

 antennae extend to the eye; first joint oblong ; second joint 

 short, half as long as first ; flagellum contains six articles. 

 Second pair of antennge extend to the 

 posterior margin of the first thoracic Fig. 11. 



segment ; flagellum contains about 

 ten articles. 



Tlioracic segments are subequal ; 

 the first is a little longer than any 

 of the others. 



The penultimate abdominal seg- 

 ment consists of several coalesced ^^„^,„^,^^^;^^^^_ xl3i_ 

 segments, as indicated by the suture- Abdomen aud last two 

 lines. Tlie terminal segment is tri- thoracic segments. 

 angular, with a small median excava- 

 tion at i(s extremity, 'J'he lower part of this segment is 

 quite flat, the slope being gradual from the convex upper 

 part or base of segment to the extremity. 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 tiie surface. 



Type. No. 22571, U.S. N. M. 



13. Sphjeroma, Latreille. 

 Analytical Key to the Species o/ Sphaeroma. 



a. Body widening gradually from head 

 backwards. Thorax transversely 

 ridged and provided with three longi- 

 tudijal rows of small tubercle?. 

 Branches of the uropoda very large, 



expanded 25. S. amplicauda, Stimpson. 



a . Body not increasing in width. Sur- 

 face of thorax smooth. Branches of 

 the uropoda not expanded. 

 I, Extremity of abdomen produced in a 



rhomboid process 26. S. rhomburum, sp. n. 



h'. Extremity of abdomen not produced. 



c. Surface of abdomen tubercular . . 27. "S". octoncum, sp. n. 

 c'. Surface of abdomen smooth .... 28. ^S. oregonensis, Dana. 



