a A. NAT.. 
VOL. XVHf.. No. 4. the KfUiS OF A FKKSH WATER KNAfb. 
THE EGGS OF A FRESH WATER SNAIL. 
AMERIA TENUISTRIATA Sowerby. 
By A. K. Beasley. 
Two specimens of the fresh water snail Ameria temdstriata 
Sowerby were taken from the Ri\'er Torrens, Adelaide (the 
type locality of the species) in November 1936, and placed in a 
half-gallon jar containing several Rice Fish. 
From March to May 1937, five batches of eggs were laid by 
the s, nails. The first three batches were laid from eight to four- 
teen days apart, but the last two took longer, from three to four 
weeks apart. The eggs were laid in groups of ten to fifteen 
covered with a transparent film of jelly-like consistency, deposited 
on the inner surface of the jar and in one case on a stone at the 
bottom of the jar. 
The eggs hatched out in three weeks from the date of laying 
of the respective batches. The young snails of the first batch 
from eggs laid in March attained an average length of 4 mm. in 
two months. 
At this stage these young snails of the first batch were 
placed in two jars, the smaller jar containing Rice Fish and weed, 
the larger with weed alone. 
It was noticed that the snails in the smaller jar with the 
fisli grew much more rapidly than those in the larger jar without 
fish. After ten weeks, the snails in the smaller jar averaged 6 
mm. in length, while those in the larger, without fish, averaged 
4 mm. in length. It is usual for snails to vary in size in com- 
parative proportion with the bulk of water in which they are 
reared, or, as some say^ in proportion of the respective surface 
area of the water. The jars in this case were dissimilar in size 
but the water surface area was approximately the same. 
Fish food was supplied to the fish in thte smaller jar. Did 
this last and only different condition in the two jars account 
in some way for the quicker growth of the snails in the smaller 
jar? 
