freely extended into the water, and the mantle-edges expanded; when the vase was moved or otherwise shaken, the animal contracted the mantle over its back, and descended "head foremost, as it were dropping down to the bottom, leaving a mucous filament attached to the glass"; subsequently, Gray adds, it ascended by the filament, rising thus towards the surface, and becoming attached to the glass as before.[1]
Limapontiidæ.
A supposed planarian-worm, Planaria variegata—probably a Limapontia[2]—was observed by Dalyell to be liable, in crawling up the side of a vessel, to drop to the bottom, its descent being apparently retarded, the observer says, by an invisible thread.[3]
ASPIDOBRANCHIATA.
In the whole of the Aspidobranchiata we have but a single observation, and this, it is said, requires confirmation. It is not surprising that no case of spinning occurs among the Limpet and Limpet-like families; but the absence of records for the land operculates of the order—Helicina, &c.—is less easy to understand, especially in view of the fact that several of the land operculates regarded as Pectinibranchiata are known to suspend themselves. The Aspidobranch said to be a spinner is our little fresh-water nerite (Neritina fluviatilis), whose name appears in this capacity in most of the books; its only claim to notoriety in this respect, however, rests upon the fact that it was listed by Mr. Warington (with several air-breathing Water-Snails) as having been observed by him to spin.[4] No particulars are given, and it is supposed by Mr. Tye that the observer may have been mistaken.[5]
- ↑ Gray, 'Annals and Magazine of Natural History' (3), iv. (1859), pp. 239–40.
- ↑ Johnston, 'Catalogue of the British Non-parasitical Worms in the British Museum,' 1865, p. 12.
- ↑ Dalyell, 'The Powers of the Creator displayed in the Creation,' ii. (1853), pp. 115–6.
- ↑ Warington, 1854, l.c.
- ↑ Tye, 1874, l.c.; 1878, l.c.
