618 GEOLOGICAL SUEVEY OF THE TERRITOEIES. 



SYNOPSIS OF THE FEESH-WATER PHYLLOPODA NORTH OF MEXICO. 

 Order Phyllopoda. 



Family 1, Estheriad^. — Body compressed, with from 10 to 27 feet, 

 inclosed in a bivalve-shell. 



Limnetis. — Shell small, less than two lines in length, round, globose, 

 without lines of growth or umbones ; feet-bearing segments from 10 

 to 12. (Fig. 3.) 



L. Gouldii, Baird (Annals and Mag. Nat. Hist., 1862, p. 393).— Shell 

 with numerous deep punctures scattered over the surface, with the place 

 of insertion of the adductor muscle very smooth and shining. Canada 

 and Massachusetts. 



L. graciliGornis, Pack. (Amer. Journ. Sc, 1871). — Differs from L. 

 Gouldii in the long, slender, second antennse, which have about 20 joints. 

 The keel on the front of the head does not reach to the front edge, 

 while in X. Gouldii it does; shell of the same form, but much larger 

 than in L. Gouldii. Length of shell, 0.17 inch ; breadth, 0,16 inch. 

 Texas. In fresh-water pools. 



Limnadia. — Shell large, with few (4 or 5) lines of growth, subtriangu- 

 lar or broadly ovate ; animal with a knob like projection (" Haftorgan ") 

 above the eyesj second antennae with 9 or 10 joints to the flagella; 

 from 18 to 26 feet. Males (only known in an Australian species, Glaus.) 

 with large, clumsy hooks on the ends of the first ]Jairof swimming-feet ; 

 body much smaller than in EstJieria. 



L. Americana^ Morse (Proc. Bost. Soc. Nat. Hist.), (Fig. 4). — Shell large 

 broad-oval, with 18 lines of growth, smooth and shining ; allied to L. 

 gigas of Europe. Length of shell, 0.55 inch. Massachusetts. 



L. [Eulimnadia) Agmsizii, Pack. (Sixth Rep. Peab. Acad., 1874), (Fig. 

 5). — Shell narrow-ovate, rather prominent behind the umbones, with 4 

 lines of groN#fch. Animal with 18 feet, and antennte with 9-jointed 

 flagella. Length of shell, 0.25 inch. Penikese Island, Massachusetts. 



L. [Eulimnadia) Texmia., Pack. (Amer. Journ. Sc, 1871). — Shell nar- 

 rower than in L. Agassizii, more oblong, with 5 lines of growth. 

 Animal with 10 joints in the flagella; 18 pairs of feet; and with a 

 larger telson than in L. Agassizii. Length of shell, 0.27 inch. Texas. 

 " Quite common in many x)laces in Western Texas in the early spring. 

 It occurs in muddy pools made after rains, and totally disappears with 

 the first drying of the pools ; occurred with Limnetis and ^treptocepha- 

 Zms." — (Belfrage.) 



Limnadella coriacea (Haldeman). — This genus was founded by Girard 

 (Proc. Phil. Acad. N. S., 1854, p. 3) under the name Limnadella Kitei. 

 It was previously described by Haldeman as Limnadia coriacea in the 

 same proceedings (vol. 1, p. 184, 1842). It is said to have the eyes united 

 into one, with 24 pairs of feet. Shell elliptical; light or dark-brown, 

 spotted with black, three lines in length. Ohio and Pennsylvania. 

 Grube thinks this may possibly be a species of Estheria. It is very 

 desirable to rediscover this species. 



Estheria. — Shell oval, more or less globose, CyclasWke^ with numer- 

 ous lines of growth, amber-colored. Animal without a haftorgan ; second 

 antennae with from 11 to 17 joints to the flagella ; from 25 to 27 seg- 

 ments in the body behind the head, and 24 to 28 feet ; anterior feet in 

 the males with clumsy hooks. • 



E. Californica, Pack. (Sixth Rep. Peab. Acad. Sc, 1874), (Fig. 6). — 

 Shell remarkably thin, so that at first sight it would be mistaken for a 

 Limnadia^ subtriangular ; umbones very small, situated much nearer 



