

2985 CRUSTACEA. 



below slightly arcuate, and on the hack scarcely at all gibbous, 

 length three times the breadth and twice the height, front, back 

 and lower margins pubescent. Eye placed near the margin. Ante- 

 rior antennae seven-jointed, setae as long as half the body, or a little 

 longer. 



Plate 90, fig. 7 a, side view, enlarged; b, upper view of shell; c, 

 side view of animal, shell removed. Also, figure 1 b, second pair of 

 antennae; c, mandibular foot; e, maxilla of second pair; /, first pair 

 of legs. 



From small fresh-water pools, to the southwestward of Valparaiso. 

 Collected in May, 1839. 



Length, one-sixteenth of an inch. Form, in a vertical view, narrow 

 ovate, with the extremities obtuse. Colour, brownish yellow. Swims 



freely. 



The figures referred to exhibit the characters of the several or- 

 gans. The anterior antennas are seven-jointed. The basal joint is 

 largest ; the third longer than the second ; the following four gra- 

 dually diminishing and bearing the long setae. These antennae may 

 be curved backward by the animal along the back of the shell. The 

 posterior antennas are large and stout, five-jointed, the joints oblong 

 and subequal, excepting the apical, which is very short and small. 

 The third joint is rather longer than the fourth, nearly twice as long 

 as the second. The organ terminates in several stout hairs, which are 

 rather longer than the penult joint. The apex of the third joint is 

 also furnished with several long and stout, hairs. 



The mandibular feet consist of the mandible, proceeding from a 

 stout base, and a four-jointed extremity, commonly called the palpus. 

 The mandible is a narrow corneous process, curving inward and den- 

 tated at apex. The second and fourth of the following joints are 

 short, and the last two are furnished with short setae. 



The first pair of maxillae are lobed below and furnished with a 

 number of short and stout setae. Attached to the base, projecting 

 above, along the side of the animal, there is a broad lamellar appen- 

 dage, somewhat oblong triangular in form, but with curving sides, 

 which is coarsely pectinated on its posterior convex side, and furnished 

 with long and stout setae. 



