178 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Coloration: Moderately transparent with a reddish tinge to cephalothorax, chitin of posterior 
edges of thoracic segments, lateral points of last thoracic segment, genital orifice, bristles of outer 
and sometimes of inner rami of feet, and the eighteenth and to some extent the nineteenth joint of the 
grasping antenna blackish brown. 
Length of female, 1.95 to 2.4 mm. ; of male. 1.7 to 2.12 mm. 
A considerable number of both sexes of this handsome and widely distributed species were taken 
in Gulf Stream July 25 and 29, 1899. 
Family PONTELLIDiE. 
LABIDOCEKA Lubbock. 
Fourth and fifth thoracic segments fused; head sometimes with lateral hooks; one pair of dorsal 
eye lenses, which are larger in male than in female; ventral eye pyriform; rostrum without lenses, 
its prong short, pointed; lifth thoracic segment produced on either side into a process or point, not 
always symmetrical; abdomen of female with two or three segments; genital segment and sometimes 
also furca asymmetrical; in male symmetrical. Anterior antennae of female 23-jointed; in right one 
of male the thirteenth and fourteenth and the nineteenth to twenty-first joints fused. Mandibular 
blade with hook-like, pointed teeth. Second basal joint of maxilla about twice as long as second 
inner lobe; third inner lobe present. Posterior maxilliped 6-jointed (terminal joint very minute). 
Inner ramus of first pair of feet 2-jointed. 
Female: Cephalothorax 5-jointed; rostral hooks rather strongly ehitinized. Anterior antenme 
23-jointed, joints 6 and 7 and 24 and 25 fused, but there are other incompletely separated joints ; some 
of the bristles on the proximal and distal joints plumose, sesthetasks filiform. In posterior antennse 
the distal basal joint is almost completely fused with proximal joint of inner ramus; outer ramus 
nearly as broad as inner and as long as proximal joint of inner ramus, or somewhat longer; terminal 
joints of outer ramus reduced. Mandible with rather long basal and 5 to 7 teeth on its blade. Distal 
basal joint of maxilla with rami bent over to outside; first outer marginal lobe short, with 7 bristles, 
second with one plumose bristle; first inner marginal lobe relatively small, second about half as 
long and broad as distal basal joint which is fused with first two joints of inner ramus. Anterior 
maxilliped stout and provided, especially on its distal half, with robust hooked and curved bristles. 
Posterior maxilliped in its entire form similar to that of Calanopia, but its second basal joint and 
inner ramus are longer and the latter is only 4-jointed, first to fourth pair of feet with 3-jointed outer 
and 2-jointed inner rami; first basal joint with a plumose inner marginal bristle on all pairs, second 
to fourth pairs with short plumose outer marginal bristle; number of bristles on rami as in Calanopia ; 
fifth pair of feet abortive, consisting on either side of a 2-jointed basal and two 1-jointed rami, of 
which only the inner is sometimes produced into a papilliform appendage. 
Male: Sexual differences in the structure of the trunk (eyes), anterior antenme, and fifth pair of 
feet. Dorsal eye lenses larger than in the female, contiguous in the median line ; last thoracic segment 
symmetrical or with more strongly developed right posterior corner. Abdomen with 5 segments, 
symmetrica] ; genital opening sinistral. Left anterior antenna with longer :esthetasks, and sometimes 
also with other modifications, which remind one of the peculiarities of right anterior antenna; in the 
latter joints 6 and 7, 13 and 14, and 19 to 21 are fused, whereas the twenty-second, twenty-third, and 
twenty-fourth to twenty-fifth remain separate, middle joints quite strong^ iucrassated, and the two 
in front and behind articulation are provided with furrowed ridges; in some species, perhaps in all, 
the eighteenth can be drawn up against the seventeenth toward posterior margin of latter. Fifth 
pair of feet consisting on either side of four joints, of which the two distal ones of right foot con- 
stitute powerful forceps; left foot sometimes with a rudiment of an inner ramus. 
16. Labidocera aestiva new species. 
Female: Cephalothorax evenly rounded anteriorly, devoid of crista on front or hooks on front or 
sides of the head- Last thoracic segment symmetrical, produced on either side into a sharp point. 
Abdomen consisting of 2 segments, first much longer than second, perfectly symmetrical and pro- 
jecting over second, covered with minute hairs on sides. Genital orifice in middle of its ventral 
surface. Second abdominal segment about twice as long as broad. Furca symmetrical, its limbs 
at least 21 times as long as broad. Anterior antennae reaching to hind end of genital segment. Fifth 
pair of feet symmetrical ; outer ramus terminating in 3 teeth, the middle nearly twice the length of 
other two; inner ramus more than half the length of outer, articulating with basal, and ending 
in a single strong, pointed tooth. 
Male: Differs from the female in following characters: Eyes with larger lenses, nearly con- 
