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SECTION D.—NATURAL HISTORY, INCLUDING PHYSIOLOGY.¹

'On the Occurrence on the British Coast of a Burrowing Barnacle, being a type of a new order of the class Cirripedia,' by Mr. A. HANCOCK.² — The animal which was the subject of this paper is called by the author Alcippe lampas. It inhabits the dead shells of various species of mollusca, which it appears to penetrate, and constructs for itself a residence by some process of boring. The author had an opportunity of watching its developement from the egg; and during the early parts of its existence it presented all the characters of many of the forms of entomostracous Crustacea. The author made some remarks on the relation of this animal to the other orders of Cirripedes, and proposed to constitute for it a new order which he called Cryptosomata. The paper was illustrated by drawings of the animal and dissections of some of its parts.

Mr. DARWIN remarked that having been employed for a considerable time in drawing up a monograph on the Cirripeda for publication by the Ray Society, he felt great interest in Mr. Hancock's paper—more especially as he had collected in South America an allied form, inhabiting cavities in the Concholepas Peruviana. Its main affinity to the genus described by Mr. Hancock lies in the number and position of the cirri and the great developement of the labrum:—the metamorphosis and organs of generation appear to be considerably different. Mr. Darwin stated that he possessed the type of another and quite distinct order of Cirripedes, entirely destitute of any shell, covering, or peduncle, without cirri, and with a suctorial mouth of very peculiar structure. Having remarked on the vast external differences between the common cirripedes and such forms as the last mentioned and that described by Mr. Hancock, and that inhabiting the Concholepas, Mr. Darwin stated that the main and unfailing character of a cirripede consists in the manner in which it becomes attached to foreign bodies. This is effected at first by the voluntary act of the larva, or more strictly pupa; afterwards a thick fluid or soft tissue debouches by the penultimate or ultimate segment of the prehensile antennæ, and so permanently attaches them to the surface: the antennæ are thus preserved, whilst all the other external organs of the pupa are moulted and lost. During the continued growth of the cirripede, the cementing substance in many genera is emitted from fresh orifices placed symmetrically round, but further and further from the centre of the basis. The most remarkable circumstance with respect to this cementing substance is that it is certainly secreted from glands which are actually continuous portions of the branching ovarian tubes or cæca. Finally, Mr. Darwin observed, that had Mr. Hancock examined specimens, instead of drawings, of the Lithotria in the rock, he would almost certainly have acknowledged its power of excavating cavities.—Prof. MILNE-EDWARDS³ suggested that the secretion by which the cirripedes were enabled to attach themselves to foreign bodies was produced by a gland at the base of the antennæ, similar to that which occurs in some species of macrourous Crustacea.—Mr. DARWIN in reply stated that the gland in the cirripedes was truly ovarial.—Prof. ALLMAN⁴ referred to the instance of a burrowing barnacle which had been discovered in the shells of some turtles brought from the West Indies, and described by the Rev. W. Hincks.⁵ It was a large species, measuring an inch and three-quarters.—Mr. JEFFREYS⁶ inquired if the cirripedes were in the habit of moulting.—Mr. DARWIN stated that their life was very active and their changes frequent, and some species moulted twice in a week.—Dr. MACDONALD⁷ thought that the structure of Mr. Hancock's animal and its earlier changes would throw some light on the structure of Trilobites.

¹ This is the report by the Athenæum's correspondent at the 19th meeting of the British Association for the Advancement of Science held at Birmingham in 1849. Hancock's paper on a new genus of boring Cirripedia (Trypetesa lampas) read to section D (natural history, including physiology) was not published in the Report of the meeting in 1850. A slightly altered version was published in Annals and Magazine of Natural History (Hancock 1849b).

² Albany Hancock (1806-1873), zoologist and palaeontologist. See Correspondence vol. 4.

³ Henri Milne-Edwards (1800-1885), French zoologist, professor of entomology, Muséum d'Histoire Naturelle, 1841.

⁴ George James Allman (1812-1898), botanist and zoologist.

⁵ Thomas Hincks (1818-1899), clergyman and zoologist.

⁶ John Gwyn Jeffreys (1809-1885), zoologist, conchologist and lawyer.

⁷ John Denis Macdonald (1826-1908), naval surgeon.