SHRIMPS OF THE GENUS BETAEUS — HART 443 



fifth plus palm. Second joint longer than subequal third and fourth. 

 Fingers subequal to, or longer than, palm. 



Third leg (fig. 41) relatively stout, slightly flattened, reaching to 

 fingers of cheliped. Ischium about % length of merus, which is slightly 

 dilated, has movable spine. Carpus stout, nearly twice length of 

 ischium, with two ventral terminal spines. Propodus elongate, sub- 

 equal to merus, with double row of spines on ventral margin (terminal 

 pair much stouter than others). Dactylus (fig. 42) stout, with 

 curved corneus tip and bristles on slight elevation dorsally. 



Fom'th leg very like third but somewhat smaller. 



Fifth leg more slender. Ischium about K length of merus. Undi- 

 lated merus with movable spine, longer than propodus, twice as long as 

 carpus. Propodus with transverse rows of bristles distally on outer 

 face as well as double row of spines on ventral margin. 



First pleopod with slender endopodite about % length of exopodite. 

 Second pleopod with endopodite slightly shorter, narrower than ex- 

 opodite. Appendix interna straplike. 



Uropod (fig. 27) with distal margin of peduncle scalelike, produced 

 into two teeth, outer of which stouter, longer, separated by curved 

 margin armed with long bristles. Another tooth median to these. 

 Proximal part of exopodite with large posterolateral tooth, dorsal to 

 large spine, which is nearly as long as distal section. Dorsal surface 

 of endopodite with bristles, all posterior margins fringed with long 

 plumose setae. Exopodite slightly longer than endopodite, both 

 longer than telson, 



Male. — Similar to female except carapace and abdomen slightly 

 more slender and setae on first pleuron sparse, not plumose. Small 

 individuals have chelipeds very like those of females but proportion- 

 ately somewhat larger. Large males develop very large chelipeds, 

 with wide gape, big teeth, and fingers touching only at the tips (fig. 

 34). When the carapace length is more than 9 mm., the hand may be 

 longer than the carapace and, in some instances, even Iji this length. 

 Appendix masculina of second pleopod straplike; terminating in a 

 brush of bristles and somewhat longer than appendix interna. 



Color. — Published records give the color of the living animal as 

 olive-green, olive-brown, uniform red-brown, or blue-green, with a 

 Hght middorsal stripe, reddish legs with clear white tips, and dark 

 tail fan with yellow setae. 



Size. — Carapace length of smallest ovigerous female 7.8 mm. ; 

 largest female 14.5 mm.; males 4-16 mm. Length of chela of largest 

 female 11.3 mm. and of largest male 23.5 mm. 



Range. — Tepoca Bay, Gulf of California, Mexico (about 30° N, 

 113° W) to Elkhorn Slough, Monterey Bay, Calif. 



Habitat. — Tide pools, under rocks, in eelgrass, in crevices among 



