36 CRUSTACEA—BRANCHIOPODA CHAP. 
appendage, 2-jointed, the second joint lamellar. A. salina, 
Linn.—Brine pools of the Palaearctic region. 
c. Hinder abdominal segments united with telson to form a fin; anal 
lobes absent. 
Thamnocephalus, Packard—Head with a branched median pro- 
cess of unknown nature. Only species 7. platywrus, Packard 
—Kansas, U.S.A. 
B. Nineteen pairs of praegenital ambulatory limbs. 
Polyartemia, Fischer—Second antennae of ¢ forcipate ; ovisac 
of @ very short. Only species P. forcipata, Fisch. 
Fam. 2. Apodidae.!—Carapace well developed as a depressed shield, 
covering at least half the body. Eyes sessile, covered; no male clasping 
organs ; anal lobes long, jointed cirri. 
Apus, Scopoli—Telson not produced backwards over the anus ; 
endites of first thoracie limb very long. A. caneriformis, 
Schaeffer—Britain, Europe, Algiers, Tunis. A. australiensis, 
Central Australia. 
Lepidurus, Leach—Telson produced backwards to form a plate 
above the anus ; endites of first thoracic limb short. L. pro- 
ductus, Bose. — Central Europe. JL. viridis, Southern 
Australia, New Zealand, L. patagonicus, Bergh, Argentines. 
Fam. 3. Limnadiidae.—Body compressed ; carapace in the form of a 
bivalve shell, the two halves capable of adduction by means of a strong 
transverse muscle; second antennae biramous, alike in both sexes; in the 
male, the first or the first and second thoracic limbs prehensile; telson 
laterally compressed. 
A. Only the first thoracic limbs prehensile in the male; the carapace 
spheroidal, without lines of growth; head not included within 
the carapace-chamber. 
Limnetis, Lovén—Compound eyes fused ; anal spines absent ; 
ambulatory limbs 10-12. JL. brachyura, O. F. Mill (Fig. 3, 
p. 21).—Norway, Central Europe. 
B. The first and second thoracic limbs prehensile in the male; carapace 
distinctly bivalve, enclosing the head, with concentric lines of 
growth round a more or less prominent umbo. 
Eulimnadia, Packard—Carapace narrowly ovate, with few (4-5) 
lines of growth. E#. mauritani, Guérin—Mauritius. £. 
terana, Packard—Texas, Kansas. 
Limnadia, Brongniart—Carapace broadly ovate, with numerous 
lines of growth, without distinct umbones; L. lenticularis, 
Linn.—Northern and Central Europe. 
Estheria, Riippell—Carapace with well-marked umbones and 
numerous lines of growth, oval; E. tetraceros, Kryneki— 
Central Europe. 
Leptestheria,? G. O. Sars—Carapace compressed, oblong. Ros- 
1 Bernard, Joc. cit. p. 19; Baird, Proc. Zool. Soc. 1852, p. 1; Sayce, Proc. Roy. 
Soc. Victoria, xv., 1903, p. 224. 
2 Sars, Arch. f. Math. og Naturvidensk. xx., 1898, Nos. 4 and 6. 
