Prices given for Shells.—Very high prices have occasionally been given for individual specimens, particularly about thirty or forty years ago, when the mania for collecting was at its height. In those days certain families, such as the Volutidae, Conidae, and Cypraeidae, were the especial objects of a collector’s ardour, and he spared no expense to make his set of the favourite genus as complete as possible. Thus at Stevens’ auction-rooms in Covent Garden, on 21st July 1854, one specimen of Conus cedo nulli fetched £9: 10s., and another £16, a C. omaicus 16 guineas, C. victor £10, and C. gloria maris, the greatest prize of all, £43: 1s. At the Vernède sale, on 14th Dec. 1859 two Conus omaicus fetched £15 and £22, and a C. gloria maris £34. At the great Dennison sale, in April 1865, the Conidae fetched extravagant prices, six specimens averaging over £20 apiece. Conus cedo nulli went for £18 and £22, C. omaicus for £12, C. malaccanus for 10 guineas (this and one of the cedo nulli being the actual specimens figured in Reeve’s Conchologia Iconica), C. cervus for £19 and C. gloria maris for £42. On 9th May 1866 a Cypraea Broderipii was sold at Stevens’ auction-rooms for £13, and at the Dennison sale a Cypraea princeps fetched £40, and C. guttata £42. The Volutidae, although not quite touching these prices, have yet done fairly well. Mr. Dennison’s Voluta fusiformis sold for £6: 15s., V. papillaris for £5, V. cymbiola for £5: 15s., V. reticulata for eight guineas, and two specimens of the rarest of all Volutas, V. festiva, for £14 and £16, both being figured in the Conchologia. At the same sale, two unique specimens of Oniscia Dennisoni fetched £17 and £18 respectively, and, at the Vernède sale, Ancillaria Vernèdei was bought for £6: 10s., and Voluta piperata for £7: 10s.
A unique specimen of a recent Pleurotomaria (quoyana F. and B.) was purchased by Miss de Burgh in 1873 for 25 guineas, and another species of the same genus (adansoniana Cr. and F.), of extraordinary size and beauty, is now offered for sale for about £100.
Bivalves have never fetched quite such high prices as univalves, but some of the favourite and showy genera have gone near to rival them. On 22nd June 1869, at Stevens’, Pecten solaris fetched £4: 5s., P. Reevii £4: 8s., and Cardita varia 5 guineas. Mr. Dennison’s specimens of Pecten subnodosus sold for £7, of Corbula Sowerbyi for £10, of Pholadomya candida for £8 and £13, while at the Vernède sale a Chama damicornis fetched £7.
CHAPTER V
REPRODUCTION—DEPOSITION OF EGGS—DEVELOPMENT OF THE FERTILISED OVUM—DIFFERENCES OF SEX—DIOECIOUS AND HERMAPHRODITE MOLLUSCA—DEVELOPMENT OF FRESH-WATER BIVALVES
Reproduction in the Mollusca invariably takes place by means of eggs, which, after being developed in the ovary of the female, are fertilised by the spermatozoa of the male. As a rule, the eggs are ‘laid,’ and undergo their subsequent development apart from the parent. This rule, however, has its exceptions, both among univalve and bivalve Mollusca, a certain number of which hatch their young from the egg before expelling them. Such ovoviviparous genera are Melania, Paludina, Balea, and Coeliaxis among land and fresh-water Mollusca, and Cymba and many Littorina amongst marine. The young of Melania tuberculata, in Algeria, have been noticed to return, as if for shelter, to the branchial cavity of the mother, some days after first quitting it. Isolated species among Pulmonata are known to be ovoviviparous, e.g. Patula Cooperi, P. Hemphilli, and P. rupestris, Acanthinula harpa, Microphysa vortex, Pupa cylindracea and muscorum, Clausilia ventricosa, Opeas dominicensis, Rhytida inaequalis, etc. All fresh-water Pelecypoda yet examined, except Dreissensia, are ovoviviparous.
The number of eggs varies greatly, being highest in the Pelecypoda. In Ostrea edulis it has been estimated at from 300,000 to 60,000,000; in Anodonta from 14,000 to 20,000; in Unio pictorum 200,000. The eggs of Doris are reckoned at from 80,000 to 600,000, of Loligo and Sepia at about 30,000 to 40,000. Pulmonata lay comparatively few eggs. Arion ater has been observed to lay 477 in forty-eight days (p. [42]). Nests of Helix aspersa have been noticed, in which the number of eggs varied from about 40 to 100. They are laid in little cup-shaped hollows at the roots of grass, with a little loose earth spread over them. The eggs of Testacella are rather large, and very elastic; if dropped on a stone floor they will rebound sharply several inches. The Cochlostyla of the Philippines lay their eggs at the tops of the great forest trees, folding a leaf together to serve as a protection.
The eggs of the great tropical Bulimus and Achatina, together with those of the Macroön group of Helix (Helicophanta, Acavus, Panda) are exceedingly large, and the number laid must be decidedly less than in the smaller Pulmonata. Bulimus oblongus, for instance, from Barbados, lays an egg about the size of a sparrow’s (Fig. [38]), Achatina sinistrorsa as large as a pigeon’s. The Cingalese Helix Waltoni when first hatched is about the size of a full-grown H. hortensis. There is, in the British Museum, a specimen of the egg of a Bulimus from S. America (probably maximus or popelairanus) which measures exactly 1¾ inch in length.
The Limnaeidae deposit their eggs in irregular gelatinous masses on the under side of the leaves of water-plants, and on all kinds of débris.
Fig. 38.—Newly-hatched young and egg of Bulimus oblongus Müll., Barbados. Natural size.