148 ON SPECIES OF OSTRACODA FOUND 
water in this pond is of variable temperature, but generally 
sufficiently hot to steam copiously. At the time the species was 
taken the water was found to be ‘‘over 100° Fahr.” This high 
temperature seemed favourable to the development of Entomos- 
traca ; and the luxury of a warm bath was shared by C. aculeata, 
with C. strigata ? and vidua, Candona reptans, Cyclops quadr.cor- 
nis, and Daphnia vetula. Mr. Brady has since taken the species 
in Hylton Dene, and remarks that the ‘specimens from this 
locality showed the same lively habits, and in the same manner 
kept generally near the surface, as those from the hot water 
reservoir. It seems, he adds, quite a gregarious species, and 
swarms upon any little vegetable tuft it may find in a bottle, 
seeming to avoid the soil as much as possible. It is by far the 
most active species of the genus that I have seen.” It has been 
found during the autumn in a third locality by myself, namely, 
in Cowpen Marshes, near Stockton-on-Tees. 
Genus Cannona, Baird. 
38. CANDONA SERRATA, n. sp. (PI. III. figs. 1-6.) 
Forma elongata, aliquantum cuneiformis; margo dor- 
salis antice valde elevatus, inde ad extremitatem 
posteriorem descendens; ventralis subrectus; ex- 
tremitates rotundate; altitudo maxima ante medium 
sita; ita ut antica pars quam postica multo est altior. 
Forma desuper spectata compressa; antica pars pos- 
tice equalis; latitudo maxima mediana. Valvarwm 
superficies foveolis impressa sparsisque pilis obsita; 
ad extremitates inferne aculeis brevibus, crassis, 
externe directis, marginata. Color cinereus, macula 
centrali ovali, atque zona marginali pallidis pictus. 
Long. ,°; unc. ; lat. vix ,% une. 
Habitat stagna limpida prope Sedgefield in regione 
Dunelmensi. 
Valves elongated, somewhat cuneiform; dorsal margin greatly 
raised in front, thence gradually descending to the posterior ex- 
tremity ; ventral margin nearly straight; anterior and posterior 
margins rounded ; point of greatest height situated in front, the 
hinder portion of the valves being much narrowed. Surface of 
