544 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 94 



First antennae 8-segmented, the two basal segments long and cylin- 

 drical, the six distal segments much shorter and about as wide as long. 

 Second antennae 4-segmented, the first and third segments each four 

 times as long as the second, the end segment a stout curved claw. First 

 four pairs of legs biramose, rami 3-segmented and about equal in 

 length with the spines arranged as in figures 223-225. Fifth legs 

 uniramose and 3-segmented, the two basal segments short and cylin- 

 drical, the end segment enlarged into a vertical circular disk curved 

 like a reflector with the concave side toward the genital segment and 

 fitting over the convex surface of the latter. Eggs carried in two 

 ovisacs, each cylindrical and containing three or four eggs. Total 

 length, 1.10 mm. Width of cephalothorax, 0.25 mm. 



Male. — Body similar to that of the female but a little smaller. Head 

 separated from the first segment, the two combined relatively longer; 

 second, third, fourth, and fifth segments about the same length but 

 diminishing in width like those of the female, the fifth segment about 

 half as wide as the second. Genital segment rectangular, a little longer 

 than wide with nearly straight sides. Abdomen 2-segmented, the anal 

 segment longer than the basal with a posterior median incision that 

 reaches beyond the center of the segment. Caudal rami cylindrical 

 but only one-half longer than the anal segment, each with three 

 terminal setae and two or three on the outer margin. 



First antennae 8-segmented as in the female, but here the two basal 

 segments are scarcely any longer than the others. Second antennae, 

 mouth parts, and first four pairs of legs like those of the female. Fifth 

 legs 3-segmented and uniramose but the end segment is not enlarged 

 as in the female. Total leng-th, 0.80 nnn. Width of head, 0.20mm. 



ReTnarks. — This genus is closely related to Ramsay Wright's genus 

 Myicola (1885, p. 120) from the common clam. It differs, however, in 

 the actual and relative size of the two sexes, the details of the body 

 regions, the two pairs of antennae, and the first and fifth legs. There 

 is as much difference between these parasites of the clam and the 

 oyster as there is between the hosts on which they live. 



Family CLAUSIDIIDAE 



FARM U LODES/ new genus 



Body suborbicular and stronglj^ flattened ; head fused with the first 

 segment and covered with a semicircular carapace, second segment 

 free; segments 3 to 5 fused and covered with another carapace smaller 

 than the first and extending back over the genital segment and ab- 

 domen, the latter 2-segmented. First antennae 18-segmented, with 

 many setae ; second antennae uniramose and uncinate. Mouth a long 

 and narrow sucking tube; first maxillae linear and tripartite at the 



» From parmula, a little round shield. 



