556 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 94 



last segment of the flagelliim. There is also a large spine on the 

 posterior margin of this second segment and the flagellum is 3-seg- 

 mented. The second antenna is 4-segmented, with a stout spine on 

 the basal segment and two slender spines at "the tip of the third seg- 

 ment. The sucking disks are of medium size and far forward; the 

 supporting rods in their margins are 7- or 8-segmented (fig. 51). 

 The basal segment is narrower and longer than any of the others, 

 which gradually diminish in length and width distally, the terminal 

 ones being flattened disks. The maxilliped is slender and its basal 

 plate is armed with three slender, curved spines. The first three pairs 

 of legs are of the usual pattern and there are no flagella on any of 

 them. On the fourth legs instead of the usual boot-shaped appendage 

 a flattened lamina extends backward from the basal segment. Its 

 posterior margin is divided by a shallow sinus into two rounded lobes 

 covered with stiff hairs. The second basipod segment has a row of 

 four slender acuminate spines on its ventral surface along the posterior 

 margin. Total length, 7 mm. Carapace, 4 mm. long-, 3.25 mm. wide. 

 Abdomen, 2.25 mm. long. 



Male. — Carapace elliptical, one-third longer than wide, the pos- 

 terior lobes not reaching the center of the second thoracic segment. 

 Cephalic area 65 percent of the carapace length, the compound eyes 

 larger and not so far forward as those of the female. The respiratory 

 areas are like those described for the female and are a little more 

 distinctly visible. The four thoracic segments are about the same 

 length and width but the fourth segment is narrowed posteriorly 

 to join the abdomen. The latter is longer than the four thoracic seg- 

 ments combined and one-half wider. The posterior sinus does not 

 quite reach the center and is broadly triangular ; the caudal rami are 

 basal and only just visible dorsally. The testes are exceptionally large 

 and fill nearl}?^ the entire space in the abdomen. Each is elongate- 

 ovate, considerably narrowed posteriorly, and extends back into the 

 posterior lobe to the center of the sinus. 



The antennae and maxillipeds are like those of the female except 

 that the latter are stouter and the ventral surface of the last three 

 segments is covered with short spines. The swimming legs are long 

 and slender and none of them exhibit any accessory sex details except 

 the fourth pair (fig. 56) . Here the second basipod segment is abruptly 

 reduced in diameter on its anterior margin near the center of the seg- 

 ment. Attached to the reduced portion close to the notch is a spheri- 

 cal knob, which stands out prominently and serves as an excellent 

 character for identification of the species. Total length, 3.98 mm. 

 Carapace, 1.98 nmi. long, 1.50 mm. wide. 



Remarks. — This species is readily recognizable by the shape and 

 length of the abdomen in both sexes and by the knob on the anterior 



