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[21]. 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[22]. 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 and bivalves (_Lamellibranchiata_). I could not incorporate them in the text, for a number of necessary details as to the conditions of life are at present entirely unknown, or are at least only known in a very fragmentary manner. No statistics as to the amount of destruction suffered by the young are available, and even the number of eggs produced annually is only known for a few species. I nevertheless include Herr Clessin’s very interesting communications, as a commencement to the life statistics of the Mollusca. (1) ‘_Vitrinae_ are annual; the old animals die in the spring, after having produced the spawn from which the young develope. These continue to grow until the following spring.’ (2) ‘The _Succineae_ are mostly biennial; _Succinea putris_ probably triennial. Fertilization takes place from June till the beginning of August, and the young develope until the autumn. _Succinea Pfeifferi_ and _S. elegans_ live through the winter, and the fact is proved by very distinct annual markings. Reproduction takes place in July and August of the following year, and they die in the autumn. They continue to grow until their death.’