J.] APPENDIX. ^r^ 



months— from July to the beginning of October ; the partheno- 

 genetic females live a fortnight longer at the outside— from the 

 middle of June to October, but the later generations have a 

 shorter life. The sexual females alone live for about a year, 

 including the v^inter sleep. 



A similar course of events takes place in the genus Vespa. 

 In both these genera the possibility of reproduction is not 

 restricted to a single female in the nest, but is shared by a 

 number of females. In the genus Apis alone is the division of 

 labour complete, so that only a single female (the queen) is at 

 any one time capable of reproduction, a powder which differen- 

 tiates it from the sterile workers. 



Note 4. The Duration of Life of the Lower 

 Marine Animals. 

 I have only met with one definite statement in the literature 

 of this part of the subject. It concerns a sea anemone, — which 

 is a solitary and not a colonial form. The English zoologist 

 Dalyell, in August, 1828, removed an Actinia mesembryanthemum 

 from the sea and placed it in an aquarium \ It was a very fine 

 individual, although it had not quite attained the largest size ; 

 and it must have been at least seven years old, as proved by 

 comparison with other individuals reared from the egg. In the 

 year 1848, it was about thirty years old, and in the twenty years 

 during which it had been in captivity it had produced 334 young 

 Actiniae. Prof Dohrn, of Naples, tells me that this Actinia is 

 still living to-day, and is shown as a curiosity to those who visit 

 the Botanical Gardens in Edinburgh. It is now (1882) at least 

 sixty-one years old '^. 



Note 5. The Duration of Life in Indigenous 

 Terrestrial and Fresh-water Mollusca. 



I am indebted to Herr Clessin— the celebrated student of our 

 mollusca — for some valuable notes upon our indigenous snails 



^ Dalyell, ' Rare and Remarkable Animals of Scotland,' vol. ii. p. 203 ; 

 London, 1848. 



[^ Mr. J. S. Haldane has kindly obtained details of the death of the 

 sea anemone referred to by the author. It died, by a natural death, on 

 August 4, 1887, after having appeared to become gradually weaker for 

 some months previous to this date. It had lived ever since 1828 in the 

 same small glass jar in v^hich it w^as placed by Sir John Dalyell. It 

 must have been at least 66 years old when it died. — E. B. P.] 



