Vol. 3] Judau. — Ostracoda of the San Diego Region. 17 



Len^ith : female 0.64; male 0.62 mm. 



Distribution. Gulf of Naples (Miiller) ; Pacific Ocean off 

 San Diego, California. 



Genns Conchoecia Dana. 



The bivalved shell which completely covers the animal is elon- 

 gated, subqnadrangular, sometimes smooth, but usually orna- 

 mented with a striated or reticulated sculpture either toward 

 the margins or over the whole surface ; rostrum and rostral sinus 

 well developed; hinge process absent or only feebly developed. 

 Antennules of the male distinctly four-jointed; the second joint 

 bears a seta which lies ring-like around the frontal organ ; the 

 third bears a sensory filament and an elongated seta ; the fourth 

 joint bears one sensory filament and two elongated setae. In 

 the female, the antennules are only indistinctly jointed, slender, 

 and bear four sensory filaments and one long, slender seta. 



Antennae greatly developed; the basal joint is large, ham- 

 shaped, and bears a natatory branch at its apex which usually 

 consists of eight joints of which the first is long and cylindrical, 

 the rest short and somewhat quadrate ; each of the short joints 

 bears a long natatory seta, but the last one has more than one. 

 The secondary branch arises on the ventral edge of the basal 

 joint of the primary branch ; it consists of three joints ; in the 

 male the basal joint forms a flattened expansion, the second is 

 short and cylindrical, the third, which is lateral to the second, is 

 falcate ; the second joint bears two long setae, and the third three 

 sensory filaments ; in the female, the second and third joints are 

 fused and bear a lash of filaments. 



The basal joint of the mandible has a strong masticatory lobe 

 and a four-jointed palp whose first joint likewise has a mastica- 

 tory lobe. The maxilla consists of a two-jointed stem, with three 

 masticatory lobes and a three-jointed palp. A second maxilla is 

 wanting. 



The basal joint of the first pair of feet, sometimes called the 

 maxillary feet, bears a circular respiratory plate on the hinder 

 edge and a four-jointed branch directed backward. The second 

 pair of feet is five-jointed; in the female directed downwards; 



