RTEI.FOX : HEREDITARY riTARACTERS OF BRITISH MOLLUSCA. 273 



albplahiata and the rubella, 00345. I will deal with the "A" family 

 first. 



One of the chosen examples attained full growth in Ji^il)') 191 -> the 

 other not until May, 1913, while the F2 generation hatched out on 

 the nth September of the latter year. Eight of the.se reached an age 

 sufficient to show that they were all roseozotiata, but only one is still 

 alive and it, even in June, 19 17, is not large enough to show its 

 mature band formula. Had it been possible to carry this family for- 

 ward to another generation I have little doubt that a pure breed of 

 roseozofiata would have been established. 



To turn now to the family "B," both the selected parents w^ere 

 fully grown in July, 191 2, but no eggs were laid until the following 

 3'ear and F2 did not arrive until the ist July, 191 3. It is most 

 unfortunate that great mortality occurred in this family also and none 

 survived to attain perfection. The ground colour and banding of 

 some twenty-four can, however, be listed without possibility of error 

 as follows. Seven were bandless and yellow, libelhda 00000, the 

 rest had red shells and in this resembled the parents; two of these 

 reds had opaque black bands, five were roseozofiata and ten were 

 bandless; of the two with opaque bands one was 12345 and the other 

 00305; of the five roseozo?iata, two were 12345, ^^^^ 00305 and one 

 was 00345. Ignoring the colour variation and dealing only with the 

 bands and their absence, seventeen were bandless, three were 12345, 

 three 00305 and one was 00345. The idea that bandlessness is a 

 dominant characteristic is here shown to be well founded, but sufficient 

 specimens were not procured to be able to state that the results were 

 a "brilliant confirmation " of Mendel's law. 



General Remarks. 



It is perhaps necessary to give a few general particulars relating to 

 my experiments. In the first place the animals are kept in boxes 

 8x6x5 inches deep, with a removable tight fitting glass cover, no 

 special means of ventilation being provided. Over-dampness is, there- 

 fore, the chief thing to be guarded against and is probably the cause 

 of a good many deaths. On the other hand it permits of my being 

 away from home even up to a period of three weeks without greatly 

 interrupting the feeding and shell-making of the mollusks during the 

 period of growth; the sand at the bottom of the box keeps the air in 

 the box sufficiently moist to promote activity. For tood, slices of 

 carrot and lettuce leaves have been maintained as the principal 

 supply, with turnips, parsnips, and cabbage in case of emergency. 

 Once a week this food is changed and the interior of the boxes 

 sprinkled lightly with water during the summer months; in winter no 

 food is required and the boxes are kept as dry as is considered ad- 



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