282 



A CROSS BETWEEN LIMNiEA STAGNALiS AND 

 L. AURICULARIA. 



By GEORGE W. CHASTER. 



(Read before the Society, September 13th, iS 



On April 2nd, 1898, I received from my friend, Mr. H. E. Craven, 

 two living Limncete — one Z. stagnalis, the other Z. auricularia. 

 Two days previously he had taken them near Lichfield in the act of 

 conjugation, Z. stagnalis performing the part of male, Z. auricularia 

 that of female. The act was not observed to be reciprocal. 



The animals were placed in fresh water and supplied with aquatic 

 plants carefully freed from Mollusca. The Z. stagnalis, whose shell 

 had been much damaged in transit, only survived a couple of days ; 

 but, to my great satisfaction, the other lived and deposited two or 

 three batches of eggs, dying eventually on April 30th. The young 



Limn&a aurictdaria {A), and L. stagnalis (j5), with their progeny ; 

 magnified two diameters. 



emerged from the eggs in about a month's time, and were carefully 

 tended during the summer and autumn. In the winter and spring 

 they were neglected owing to pressure of other work, and but 

 few survived. At the end of June in the present year these had 

 reached adult age, as was evidenced by the slight reflection of the 

 outer lip, and were killed without having been observed to attempt 

 reproduction. Their shells exhibit some variation, but shew no 

 affinity to either parent, for all in their conchological characters are 

 quite unmistakably Z. peregra ! 



Now, in connection with this case, two points merit consideration. 

 We are at once confronted with the problem as to whether Z. stag- 



