PACKARD.] PHYLLOPODS OF NORTH AMERICA. 315 
“The structure of the carapace is the same as in Limnadia Hermanni, 
the surface being covered with minute dots or punctuations. 
“This species differs from the two others in the shape of the carapace 
and in having the sete of antennz and tail plumose. 
.  Hab.—St. Domingo, West Indies; M. Sallé, Mus. Brit.” (Baird.) 
Family APODIDA Burmeister. 
Head and body in front broad and flat, shovel-shaped; carapace broad 
and flat; the body cylindrical, few or numerous segments extending 
beyond the carapace; antenne small, 2d pair minute, sometimes want- 
ing; labrum large, broad, flat; feet numerous, usually 63 pairs; with 
a large coxal, maxilla-like basal lobe forming gnathites; beyond five 
subjointed endites ; the 2-4th endites in 1st pair of feet very long and 
slender, especially the 5th; gill pear-shaped or bottle-shaped ; flabellum 
triangular, simple; the 5th endite of the Ist pair of legs is sometimes 
nearly as long as the body, the 11th pair bearing egg-sacs, and in the 
male having the genital outlet. Behind the 11th pair two of the abdomi- 
nal segments bear each six pairs of appendages, there being many more 
appendages than segments to the abdomen, while a variable number at 
the end are without appendages. ‘'Telson cylindrical, either short or 
ending (in Lepidurus) in a long paddie-like outgrowth. A pair of long 
filiform jointed caudal appendages. Larva a nauplius. 
Synopsis of the genera. 
Telson ending in along paddle-shaped outgrowth.........-. Lepidurus 
Telson short, cylindrical, simple.........-....-.--.- ap Ae Ae Apus 
Genus LEPIDURUS Leach. 
Plates XV, figs. 2, 2a, 3; XVI, figs. 1, la, 16; XVII, XXI, figs. 1-6, 9, 11. 
Lepidurus, Leach. Vict. des Sc. Nat. I, 259. 1816. 
Body rather deeper, more rounded than in Apus ; the carapace longer 
in proportion to the body than in Apus. Frontal doublure much as in 
Apus, but with a rather prominent tubercle at the base of the hypostoma, 
while the latter is much larger than in Apus. Eyes asin Apus, but the 
tubercle behind the eyes is oblong-oval, instead of round, as in all the 
species of Apus I have seen. Antenne much asin Apus. Mandibles as 
in Apus, with the same number of teeth; but the dorsal mandibular 
transverse tubercle on the carapace is larger; the maxille also as in 
Apus. The endites of the Ist pair of legs are very short, the outer ones 
in some species scarcely projecting beyond the edge of the carapace; 
there are about twelve subjoints in the 5th or longest endite, and the 
ends are usually (not always) rather blunt. The flabellum is very small 
compared with that of Apus, being narrow, triangular, the distal end 
acutely pointed, the gill or gill-sac itself much as in Apus. In the suc- 
ceeding pair of legs there are no good generic differences between Apus 
and Lepidurus, though endites 2-5 are inclined to be rather the longer 
in Lepidurus. Gnathobases or coxal lobes much alike in the two genera. 
In comparing the 10th pair of feet of Apus and Lepidurus no generic 
differences are to be observed, while the 11th pair, bearing the ovisacs, 
do not essentially differ in the two genera, but afford excellent specific 
characters; however, the ovisacs in Lepidurus are considerably jarger 
and deeper than in Apus. 
