Nidification and Emhnjoloykal Development 35 



On February 15 three cajjsules were laid by the adult snails. They contained 

 three, eleven, and thirteen eggs respectively and development occupied thirteen to 

 fifteen days, from February 28 until March 12. On February 18 a capsule 9 by 6 mm. 

 was laid containing forty eggs, and on February 20 four cap.sules were deposited meas- 

 uring 6 by 5, 9 b\' 6, 6 by 5, and 6 by 4.5 mm. They contained thirty-five, thirty-three, 

 twenty-eight, and twenty eggs respectively. On March 1 and 2, two capsules were laid 

 containing thirty-one and twenty-three eggs. All of these eggs completed their de- 

 velopment in from twelve to fourteen da.ys. 



On June 5, 1932, the aquarium was examined and the shells counted and measured. 

 There were ninety-six li\ing young snails and forty-fi\e empty shells, 141 specimens 

 in all which had hatched from the capsules enumerated above. The living 3'oung snails 

 gave the following measurements: 



8 specimens 1.5 mm. in diameter with 1V> whorls. 

 18 specimens 2.0 mm. in diameter with 2 whorls. 

 3 specimens 2.3 mm. in diameter witli 2 whoi'ls. 

 ■ 40 specimens 2.5 mm. in diameter with 2 whorls. 

 20 specimens 3.0 mm. in diameter with 2 whorls. 

 6 specimens 3.0 mm. in diameter with 2^/l> whorls. 

 1 specimen 4.0 mm. in diameter with 21-) whorls. 

 Between June 5 and June 26, fifty-four young snails died, leaving fort3'-two 

 active young and three adult .snails. On August 15, only fourteen young snails 

 were alive, the great mortality being largely due to the very hot summer. The 

 measurements of these survivors are shown below: 



1 specimen 2.1 mm. in diameter with 2 whorls. 



2 specimens 2.5 mm. in diameter with 2 whorls. 



3 specimens 3.0 mm. in diameter with 2i/-i w'horls. 

 6 specimens 3.5 mm. in diameter with 2V-> whorls. 



2 specimens 4.0 mm. in diameter with 2% whorls. 



On October 23. 1932, two young snails died leaving twelve active 3'oung. On 

 December 28, 1932, four additional snails died lea\ing eight young which gave 

 the following measurements : 



1 specimen 3.5 mm. in diameter with 2V2 whorls. 



1 specimen 4.0 mm. in diameter with 2y-2 whorls. 



1 .specimen 4.0 mm. in diameter with 3 whorls. 



1 specimen 4.2 mm. in diameter with 3 whorls. 



3 specimens 4.5 mm. in diameter with 3 whorls. 

 1 specimen 4.9 mm. in diameter with 3 whorls. 



On March 12, 1933, only five young .snails remained alive, as noted below: 

 1 specimen 4.0 mm. in diameter with 21^ whorls. 



1 specimen 3.5 mm. in diameter with 3 whorls. 



2 sjjecimens 5.0 mm. in diameter with 3 whorls. 

 1 specimen 5.0 mm. in diameter with 314 whorls. 



On May 1, 1933, but two specimens remamed alive. mea.suring: 

 1 specimen 4.0 mm. in diameter with 3 whorls. 

 1 specimen 5.2 mm. in diameter with 3^/4 whorls. 



On June 25, 1933, one specimen only remained, mea.suring 6.1 mm. in diameter 

 with three and one-half whorls. This specimen had li\ed from February 28. 1932, until 

 June 25. 1933, an interval of 482 days or sixteen months. It had grown from a diameter 

 of 0.8 mm. to 6.1 mm. and the whorls increased from one to three and one-half. Adult 

 californiense measures 20 nmi. in diameter and has five whorls which would indicate 

 that the young specimen sixteen months old had made about one-third of its growth. 

 As in the cases of the other species described in this chapter, factors of volume of 

 water, food, and temperature maj^ have retarded the normal growth of the young of 

 this race. At this ratio full maturity would be attained between the third and fourth 

 years of life. 



[6] Other Records of Egg Laying 



HcUfiODUi pilshryi infracnrinatiun F. C. Baker. Sjiecimens of this species were re- 

 ceived from Mr. A. LaRocque, of the Canadian National Mu.sevmi. They were collected 

 in the Rideau River near Ottawa. Canada. On June 20 two egg cap.sules were deposited 

 each measuring 6 by 4.5 mm. in size and containing eighteen and twenty eggs. On 



