270 
HISTORY OF BRITISH CRUSTACEA. 
of movement. In a vessel in which he kept some, he fre- 
quently saw them turn head-over-heels, throwing a regular 
summersault ten or a dozen times in succession. 
Daphnia yetula, Muller, p. ; Baird. — Carapace ovate, 
small, transparent ; striated hinder extremity without spine ; 
head blunt, small, beak not very prominent. 
Hab. Ponds and ditches, in summer and autumn. 
Daphnia reticulata, J urine, sp. — Carapace rounded- 
oval, slightly greenish, surface covered with a complete 
mesh-work of small hexagonal cells ; lower extremity with a 
short spine; head rather small, without beak; sixth seg- 
ment of body with a spur. 
Hab. Ponds and ditches, in summer and autumn. 
Daphnia rotunda, Strauss. — Carapace almost quite 
round, lower extremity with a short blunt spine; colour 
reddish ; sixth segment of body without a spur. 
Plab. Ponds and ditches near London. 
Daphnia mucronata, Muller. — Carapace w r ith its front 
edge quite straight, and ending below in a spine of some 
length ; the whole creature is of a dark gray. 
Hab. Ponds about Isle worth. Dr. Baird found two 
varieties there ; one has the head rounded above, the other 
has the head ending in a sharp point directed upwards. 
