Rathbun. — 
SOUTH AMERICAN CRUSTACEA 
47 
crossed outwardly by a similar transverse ridge which is a little 
above the side margin, and is continued backward part way 
along that margin. 
Front not advanced beyond line of subhepatic region, wide- 
ning at the extremity. Orbits in front view inclined obliquely 
downward and outward, each being wider 'than half the front. 
Chelipeds pubescent on the inner side; rather- stout upper 
and lower margins of palm slightly convex; "pollex slightly 
deflexed, very short, „ triangular, 
with two small teeth on the prehen- 
sile edge. Dactidus strongly cur- 
ved down; edge with a minute spi- 
nule on the distal half. 
First and second pairs of ambu- 
latories narrow, their terminal seg- 
ments very slender and curved. 
Third pair scarcely longer than 
second, but half again as wide. i.-Ourm MAxti,Lii'Ei> of pin- 
Fourth pan' about as wide as s- ] 
lecond, anda little over half as ong, dactylus nearly straight. 
Abdomen of male with sides of penult segment concave.' 
Female. — Differs from the male in lacking the cardiac rid- 
ges; in the digits of the chelipeds being longer, and lonjitudi- 
nal in position, without teeth on the prehensile edges^^. 
Dimensions. — Lenglh of male 3.7 mm., width 6.8 mm. ; 
Tp2)e locality. — Corral, province Valdivia, five males one 
female. 
Related to P. affinis Rathbun, of Panama Bay, in the fema- 
le of which, however, a cardiac ridge is present and the thumb 
is very short and wide. \ . :4 
■ .'^^ 
Leptodius tridentatus Lenz * u^-^ 
Leptodius tridentatus Lenz, Zool. Jahrb., Suppl., Bdv V, 
p. 761, pi XXIII, figs. 7, 7a, 1902. , : ^ ^ 
Puerto Corral; C. E. Porter; February 1903; one male.^ 
This specimen corresponds to Lenz's description and figure; 
it measures 8.8 mm. long, 13.5 mm. wide. 
