STELFOX : HEREDITARY CHARACTERS OF BRITISH MOI.LUSCA. 27 1 



third band comes first, almost contemporaneously with the commence- 

 ment of growth after the young snail is hatched from the egg. The 

 fourth and fifth respectively appear next, followed sometimes at a 

 considerable interval by the second and lastly the first. The fourth 

 and fifth and the second and first sometimes come almost simul- 

 taneously (or perhaps their order of coming may even be reversed, 

 although I have not seen this occur). It will be seen, therefore, that- 

 the form 00345, for instance, may quite possibly be a 12345 with the 

 commencement of bands i and 2 abnormally retarded; or on the 

 other hand it may be due to the presence of an inhibiting factor which 

 does not act on the three lower bands; or finally it may be due to the 

 absence of the factor or factors which would, if present, produce the 

 bands. 



Experiment No. 3. Helix nemoralis L. 



The originals in this experiment consisted of eight libeliula, one of 

 them 12345, two 1(23)45, two i(23)(45) and three (i23)(45), from 

 the Co. Fermanagh hills north of Kiltyclogher, collected in July, 1909. 

 A large proportion of the shells observed in this locality were similar 

 or belonged to the var. roseozo?iaia, and the majority were very conical 

 in shape. 



Two families of the Fi generation were hatched, the first in 

 September, 1909, the second in June, 19 10. All the young shells 

 were banded and-those grown to maturity most strikingly resembled 

 the originals in their colouring, banding and conical shape. The Ft 

 never laid eggs and the last died in April, 1916. 



Experiment No. 4. Helix nemoralis L. 



Eleven or twelve var. roscozoiiata, from the same locality near 

 Kiltyclogher as the originals of the last experiment, were placed in a 

 box in July, 1909. Young appeared in the following September. 

 To my great surprise none of Fi which survived to an age sufficient 

 for the determination of their characters were roseozoftata. On the 

 other hand all possessed a reddish ground colour and five normally 

 pigmented bands, some of which in cases coalesced. Under similar 

 circumstances I am afraid that Prof. Lang would have been tempted 

 to explain this result by some elaboration of iSIendel's law, but it can 

 more easily be accounted for, I think, by supposing that the parent or 

 parents of Fi had been fertilized by one of the many shells similar to 

 those belonging to the last experiment, wliich were abundant in the 

 locality from wiiich both came. Provided that the parents were fer- 

 tilized previous to my collecting them, and that opaque or black 

 banding is dominant to translucent banding and red is dominant to 

 yellow, the Fi generation of such a cross .would naturally be red 



