On some West-Australian Entomostraca. 29 
warmest part of the summer, when the aquaria were exposed 
to the direct rays of the sun, did the specimens move with 
extraordinary rapidity, now and then stopping in order to 
feed on some nourishing matter. In proportion as the 
weather became colder, the animals assumed a somewhat 
more sluggish habit, and were more frequently seen keeping 
at the bottom, more or less deeply buried in the loose 
mud, and only at times moving freely through the water. 
Male and female specimens occurred during the whole 
season in about equal numbers, and both were very often 
seen in copulation. This form, indeed, is pronouncedly 
gamogenetic in character, like the other known species of 
the genus. 
Gen. Cypris, Müller. 
5. Cypris oblongata, G. O. Sars, n. sp. 
(PL 4, figs. 6—9). 
Specific Characters.—Shell, seen laterally, oblong 
subreniform, greatest height not attaining half the length, 
and occurring in front of the middle, anterior extremity 
broadly rounded, posterior considerably narrower, and ob- 
tusely produced, dorsal margin in female rather evenly 
arched, in male nearly straight in the middle, with an indi- 
cation of angle in front and behind, ventral margin distinctly 
sinuated:—seen from above, moderately tumid, oblong fusi- 
form in outline, greatest width not attaining the height, and 
occurring in front of the middle, posterior extremity con- 
siderably narrower than the anterior. Valves nearly equal, 
the left one having a very narrow hyaline border at each 
extremity, right valve without any marginal tubercles, 
