54 CRUSTACEA—-BRANCHIOPODA CHAP. II 
claws of telson with two accessory teeth (includes sub-genera 
Alonella, Pleuroxus, Peracantha). 
B. Body small, spheroidal ; the head depressed. Chydorus, 
Leach: compound eye present. Monopsilus, Sars: 
compound eye absent. 
Tribe II. GymNnomERA, Sars.—The carapace forms a closed brood-pouch, 
which does not cover the body ; all the thoracic limbs prehensile. 
Fam. 7. Polyphemidae: four pairs of thoracic limbs, provided with a 
enathobase. 
Fresh-water genera. 
Polyphemus, Miller, with no rudimentary 
exites on first three thoracic limbs. Bythotrephes, Leydig (Fig. 
13), with no trace of processes on the outer sides of the limbs. 
Marine genera.—Evadne, Lovén, the head not separated by a 
constriction from the thorax. Podon, Lovén, with deep 
cervical constriction. 
Fra, 24.—Leptodora hyalina, x 6. Lake Bassenthwaite. A.1, First antenna ; 
Car, carapace ; I, VI, first and sixth thoracic appendages. 
Fam. 8. Leptodoridae: six pairs of thoracic limbs, with no gnathobase. 
Only genus, Leptodora, Lilljeborg (Fig. 24), from fresh water. 
Note—For extra-European Cladocera consult Daday, “ Microskopische 
Siisswassertiere aus Patagonien und Chili,” Termés Fiizetek, xxv., 1902, p. 
201; for Paraguay, Bibliotheca Zoologica, Heft 44 ; for Ceylon, Termes Piizetek, 
xxi, 1898; and for Australia, Sars, Christiania Vidensk. Forhand. 1885, 
No. 8, and 1888, No. 7; and Arch. f. Math. og Naturvid. xviii. 1896, No. 
3, and xix., 1897, No. 1.—G. W.S. 
