PACKARD.] PHYLLOPODS OF NORTH AMERICA. 319 
pair of feet. Length of body, 35™™; length of carapace (measured along 
median line), 15™™; breadth, 17™™; length of caudal appendages, 14™™; 
antenne, 10™™, 
Po Cafion, Vermillion River, Colorado; collected by Dr. C. A. White, 
of Major Powell’s Survey. Described from specimens kindly loaned by 
Prof. H. A. Ward, of Rochester, N. Y. 
This exceedingly interesting species differs from any other known to 
me in the large, broad, bilobed telson, that of Z. glacialis being small, 
subtriangular, while in Z. productus and DL. couesti it is long and spatu- 
late. It differs from the two latter species in the longer, broader, 1st 
pair of feet, the longer body, and shorter carapace. 
The differences in the appendages in ZL. bilobatus and couesii are 
very slight; in the 2d pair of feet the accessory gill of LD. bilobatus is 
longer, less rectangularly triangular than in Z. couesii, while the pear- 
shaped gill is of nearly the same shape in both species. In both species 
the four endites are long and slender, those of Z. bilobatus being rather 
wider than in L. couesti. The scale (6th endite) is blunt, knife-shaped, 
and finely denticulate on the outside in L. bilobatus, while in L. couesia 
it is acute, shorter, and triangular? In the 2d pair of feet the scale in 
L. bilobatus is very large, stout, knife shaped, and finely denticulated 
on the inuer edge, with fine sete externally; that of LZ. couesti is one- 
third smaller and acutely triangular; the four endites are much broader 
in DL. bilobatus than in L. couesit. The accessory gill is larger and much 
the broader in L. bilobatus, the posterior end being very much produced 
in L.couesti. Inthe10th pairof limbs theendites are longer and narrower 
in L. bilobatus than in covesii, and the seale is narrower. 
The following exotic species may be referred to here: 
Lepidurus viridis Baird, Proc. Zool. Soc., London, 1850. Van Diemen’s Land. 
Lepidurus angusii Baird, Proc. Zool. Soc., London, 122, 1866. Rain pools on the Gaw- 
ler Plains, north of Adelaide, South Australia. 
APUS Schaeffer. 
Plates XV, figs. 1, 1a, 1b; XVI, figs. 2-5a; XVIII, XXXII, XXXV. 
Apus Schaeffer, Der krebsartige Kiefenfuss, 1756. Bose, Hist. des Crust. ii, 244, Pl. 
DOVE ods Latreille, Hist. des Crust. ials: iv, 195. Milne-Edwards, Hist. 
Nat. Crust. ill, 356, 1840. 
As in Lepidurus, but the carapace is shorter, the abdomen being 
longer and extending much farther beyond the hinder edge of the cara- 
pace; the 2d—5th endites of the 1st pair of legs are much longer than in 
Lepidurus, the 5th when stretched back sometimes reaching near the 
telson; the latter is short, cylindrical, without any paddle-like exten- 
sion. 
Synopsis of the species. 
Carapace, longer than in the other species; telson short, with 4 large 
centralspines SEONG ce Pe cee oe a can el ela eR ie ere A. aqualis. 
Carapace shorter than in equalis, but the telson longer. ..A. newberryi. 
Carapace shorter than in foregoing species; telson ‘With only 3 central 
TUTTE GS) ap Wd PAS eee Seen a cS A. lucasanus. 
Carapace much as in A. lucasanus; telson very short, with 5 central 
“TILT SR Regis gas aM ete ae tea tet aah et Diet ea wee A. longicaudatus. 
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