SHRIMPS OF THE GENUS BETAEUS — HART 457 



making pocket into which swollen part of palm and projection of 

 carpus fit, when "wrist" is bent. Carpus cup-shaped, with small plate 

 ventrally, covered with long soft setae dorsally. Chela (figs. 70, 71) 

 large, as long as carapace and nearly as wide, much compressed later- 

 ally with upper margin of base of fixed finger thin, sharp. Fixed finger 

 twice as wide at base as dactylus, which is longer than palm. Cutting- 

 surfaces, tips of fingers, dorsal part of fixed finger setose. Left chela 

 with large tooth medially on fixed finger, wide gape, smaller teeth 

 intermeshing proximally and terminally before crossed corneous tips. 

 Right chela with slight gape but most of small flat teeth intermeshing. 

 Hands covered mth fine short setae. 



Second leg (fig. 72) setose with ischimn and merus subequal, shorter 

 than carpus, which has first and last joints subequal and twice as long 

 as each of subequal median joints. Fmgers almost as long as palm 

 and finely spinulate on cutting surfaces. 



Third leg (fig. 79) with stout ischium. Merus inflated with large 

 movable spine on proximal part. Merus and propodus subequal in 

 length. Carpus shorter than either, with pair of stout spines and 

 setae on distal ventral margin. Propodus with stout spines and 

 setae on ventral margin and two large spines terminally. Dactylus 

 (fig. 80) short, broad, bifid, armed with few bristles. Whole ap- 

 pendage setose dorsally. 



Fom"th leg similar to thu-d but somewhat smaller. 



Fifth leg subequal in length to third but without movable spine on 

 merus, no spines on carpus. Spines on propodus small, hidden by 

 transverse bands of setae forming brush on distal third of propodus. 



First pleopod with endopodite about K exopodite in length and 

 width. Second pleopod with exopodite and endopodite slender, 

 subequal. Appendix interna large, straplike. 



Uropod (fig. 68) with posterior margin of peduncle produced into 

 two large teeth; outer distinctly larger than inner. Long bristles on 

 curved margin between teeth. Exopodite with long bristles dorsolat- 

 erally and small tooth above stout spine on posterolateral angle of 

 proximal part. Endopodite and exopodite with scattered bristles 

 dorsally. Uropods longer than telson. 



Male. — Similar to female except that chelipeds (fig. 69) are larger 

 in proportion, chela longer than carapace, antennular peduncle 

 proportionately longer, abdomen somewhat narrower. First pleopod 

 with very small endopodite. Second pleopod with appendix masculina 

 large and bristled throughout its length. Appendix interna small. 



Color. — "Nearly white" (Holmes, 1900) and red or brown with 

 kelp, and green with sea lettuce and eelgrass (MacGinitie and Mac- 

 Ginitie, 1 949) . These were identified as Betaeus harfordi but probably 

 they were B. setosus. Living specimens taken in British Columbia 



