38 PROCEEDINGS OF THE NATIONAL MUSEUM VOL, 113 
fagiieyes Island and the mainland near La Parguera, Puerto Rico, 
where the bottom is covered with turtle grass, Thalassia testudinum, 
and the associated algae, Penicillus capitatus, Halimeda opuntia, and 
Dictyota cervicornis. Simce we suspected that Pseudocyclops lived 
close to or on the bottom, we made collections with No. 10 and No. 
20 mesh nets, 1 foot in diameter, the nets towed close to the bottom 
so that they passed through the Thalassia leaves. The nets were 
towed either by hand while swimming, or from behind a boat; in the 
latter case the nets were held at the desired depth by a swimmer 
alongside them. Large numbers of Pseudocyclops were obtained by 
this method. 
Family Pseudocyclopidae Giesbrecht, 1893 
Since the relationships of the family are still uncertain, we have 
refrained from giving a family diagnosis. 
Genus Pseudocyclops Brady, 1872 
Pseudocyclops Brady, 1872, p. 431. Type species, by monotypy, P. crassiremis 
Brady, 1872; gender masculine. 
The emended diagnosis given below is based on the characters of 
the 4 new Puerto Rican species and the 10 previously described 
species. Since some of the latter species are incompletely described 
or known from only one sex, and many species, perhaps a majority, 
have not yet been discovered, the diagnosis must be considered pro- 
visional. In particular Pseudocyclops simplex Sewell (1932) differs 
from this diagnosis in its swimming leg setation and should be given 
further study. We follow Gooding’s (1957) usage of terms for regions 
of the copeped body. 
Driaanosis (emended): Body plump; head separated from or fused 
with first pedigerous segment; fifth pedigerous segment small. Uro- 
some 4-segmented in female, 5-segmented in male; genital segment 
not much produced ventrally; genital openings widely separated in 
female, male genital opening on left side; anal segment very short, 
immersed in and almost completely concealed by preceding segment. 
Outermost caudal seta spiniform; next-to-innermost seta longer and 
thicker than others. Rostrum single, strongly developed, without 
filaments, sometimes movable in male. Antenna 1 very short, 
scarcely reaching beyond head, 14-18 segmented, first segment bearing 
3 long sensory filaments (aesthetes) ; right antenna 1 of male geniculate. 
Hxopod of antenna 2 with reduced number of segments. Endopod of 
maxilla 1 elongate, setae of outer lobe reduced. Endopod of maxil- 
liped short, indistinctly segmented. 
Legs 1-4 with 3-segmented rami; outer spines of exopods robust; 
inner setae jointed near the middle, moderately thick proximal to 
