came they all disappeared. However, in aquarium B, whenever warm weather prevailed a solitary tadpole would appear from time to time, but in the coldest part of the winter no tadpoles were visible. It seems to me that when tadpoles remain as tadpoles all the winter, they must either bury themselves in the mud or else hide away among the water-weeds at the bottom of the aquarium, for I could never see any sign of them during the cold weather.

In the spring two tadpoles appeared in tank B, and only one in tank A, though no doubt several crayfish, which were living in the same aquarium, were partly responsible for the smallness of the number of survivors in the latter. Though the aquariums had plenty of water-weeds and submerged rocks, there was no place where the tadpoles could find a shallow landing-place where they would need their limbs for crawling, and the result has been that neither the lungs nor the limbs have been developed.

In autumn they would often come to the surface and take in large mouthfuls of air, as most tadpoles do, but since the winter they seem to have no inclination to come to the surface, but act to all intents and purposes similar to fish.

It has been stated that not only will tadpoles keep as tadpoles when reared under such conditions, but that they will increase in size in proportion to the size of the tank in which they are kept. Though three specimens are not sufficient to prove anything, yet the tadpoles in my aquariums do seem to uphold this fact. All of them were about 17 mm. in length when put into the tanks, and now the two in the tank holding 2 ⅓ cubic feet of water are only 25 mm. and 30 mm. respectively, while the one in the tank holding 4 cubic feet of water is now 45 mm. in length.