HARGREAVES : SINISTRAL LIMN^A I'EKEGEK. 57 



No. 6 receptacle contained two batches of eggs together. When 

 first observed tlie sinistral examples were larger than the dexlral, and 

 probably hatched out a day or two earlier from one of the masses of 

 eggs, and tlie smaller dextral ones from the other mass, as I have not 

 noticed that sinistral shells grow faster than dextral immediately after 

 being hatched. 



No. 13 consisted of several broken masses of eggs, from several 

 sinistral parents. 



The results totalled are 



696 dextral and 138 sinistral. 



Clearly the result shows that dextralism is "dominant." 



Does not this result also tend to show that this particular monstros- 

 ity produces approximately the same results as varieties under 

 Mendelian laws? The proportions are rather different but not widely 

 so. More experiments are required to correct or confirm these 

 results, as they are too few to be available for safe generalisation. 



It is interesting to note that though the egg masses were approxi- 

 mately of the same size, those resulting in " pure " sinistrals yielded 

 much smaller numbers of young than the " pure " dextrals, the 

 maximum being 22 as compared with 118. 



All the egg masses obtained where the only known parent was 

 dextral, yielded dextral young only, not a single sinistral example 

 being obtained from them. It is quite probable that the ancestors of 

 the selected examples may have been dextral for generations. Possibly 

 it may indicate that the tendency to this monstrosity exists only in 

 certain strains in the pond, and possibly even that the monstrosity is 

 transmitted only through sinistral forms, but many more batches 

 would have to be examined before one could arrive at a definite 

 conclusion. 



It would be interesting to continue the observations through 

 another generation from 



(i) The dextral forms deriven from a sinistral mother. 



(2) The sinistral forms from a sinistral mother. 



(3) Crosses between the two. 



Since this was written, Mr. Bevan, of Scarborough, has hatched 

 eggs from a dextral individual which I gave him, and amongst the 

 young were three sinistral specimens. 



