270 Mi33 H. Rlcliardson on the Isopods of the 



20. COLIDOTEA *, gen. nov. 

 57. Colidotea rostrata (Benedict). 



Idotea rostrata, Benedict, Proc. Biol. Soc. Washington, xii. 1898, 

 pp. 53, 54. 



Hub. San Pedro, California. 



21. Cleantis, Dana. 



Analytical Key to the Species of Cleantis. 



a. Fliigellum consolidated and forming a single 



piece. Sides of abdomen not separated by 



an acute tooth from rounded posterior 



portion 58. C occidentalis, sp. n. 



«'. Flagellum composed of three joints. Sides 



of abdomen separated by an acute tooth 



from rounded posterior portion 59. C. Heathii, sp. n. 



58. Cleantis occidentalism s[). n. 



Body narrow, elongate ; surface smooth. 

 Head of same width as thoracic segments and with a small 

 median anterior depression. Eyes lateral. First pair of 

 antennae consi.sting of four joints, reaching the middle of the 

 third joint of the second pair of antennre. Second pair of 

 antennaj contain six joints (five seen from a dorsal view), the 

 last joint being the flagellum. 



The thoracic segments show a gradual though marked 

 decrease in length, the first one being the longest and some- 

 what excavate on its anterior margin. The epimera of the 

 second, third, and fourth segments are short and narrow, 

 reaching but half the length of the segments, wiiile those of 

 the last three segments are broad, with tlieir posterior angles 

 produced beyond the segments. 



The abdomen is composed of four segments — three short 

 ones and the terminal segment, which bears suture-lines 

 indicative of another coalesced segment. The terminal 

 segment is rounded posteriorly. The anterior three fourths 

 of the segment is raised considerably above the posterior 

 fourth, which is flat, and there is a groove in the median line 

 on the posterior third of the anterior part of the segment. 



The legs are similar to those of the type species of the 

 genus. The three anterior pairs increase in length, the third 

 pair being the longest, and all are directed anteriorly. The 

 fnurth pair are very short and fold across the body. The last 



* See ke}' on p. L'(il tor cliaracters of genus. 



