II BRITISH GENERA OF CLADOCERA S51 
Summary of Characters of the British Genera.’ 
Tribe I, CatyptomerA, Sars.—The post-cephalic portion of the body 
enveloped in a free fold or carapace. 
A. Six pairs of thoracic feet, the first pair not prehensile (CTENOPODA). 
Fam. 1. Sididae: second antennae biramous in both sexes.  Szda, 
Straus (Fig. 11): second antenna with three joints in the dorsal 
ramus, two in the ventral; the rostrum large, the teeth on the 
telson many. Latona, Straus: second antenna with two joints in 
the dorsal ramus, three in the ventral, the proximal joint of the dorsal 
ramus provided with a setose appendage. Daphnella, Baird : second 
antenna with the joints as in Latona, but with no setose appendage. 
Fam. 2. Holopediidae: second antennae not biramous in the female; a 
rudimentary second ramus in the male. Holopediwm, Zaddach. 
B. Four to five or six pairs of thoracic feet, the anterior pair prehensile 
(ANOMOPODA). 
A. Ventral ramus of second antenna with three joints, the dorsal 
ramus with four. 
Fam. 3. Daphniidae: five pairs of thoracic feet, with a gap between 
the fourth and fifth pairs. The stomach with two forwardly-directed 
diverticula. 
i. First antennae of female short. 
a A median dorsal spine on posterior margin of carapace. 
Daphnia, O. F. Miller (Fig. 19): first antennae of female 
not mobile. The head separated from the thorax only by 
Fic. 19. — Daphnia 
obtusa, male, x 
about 50. Oxford. 
“Ales Hirst, |) ‘an 
tenna; 7.1, first 
thoracic append- 
age. 
a slight constriction or not at all. Cuticle with a quadrate 
Quekett Micr. Club, 1903-4. 
