This specimen, obtained from one of the Plymouth trawlers, consisted of a large tumour on the dorsal surface, near the left angle of the fin (see Figs. 1 and 2). Only part of the fish was available for examination, so the presence of metastases and other details could not be determined.

Corystes buries itself in sand for protection, with the tip of the antennal tube, through which enters the respiratory current, projecting. The water which enters the antennal tube cannot be quite clear: there is a hairy filter, which rejects particles of mud, etc., at the entrance to each branchial chamber. The main body of the in-current is split into right and left currents, owing to the position of the apophyses of the mandibles, and these two currents enter respectively the right and left branchial chambers. The epistomial ridge on the roof of the prostomial chamber turns aside some portion of the in-current, which portion passes out ventrally through a gap in the floor of the chamber, carrying out with it foreign particles brought in by the in-current and rejected by the sieves guarding the entrances to the branchial chambers.

Several previous authors have shown that the food of the mackerel, when in coastal waters, is of two different kinds, and that the fish adopts two distinct methods of procuring it. In the first place it feeds by a system of filtration upon planktonic organisms, and secondly upon prey of a larger character which is hunted by sight.

On looking over some hydroid material, for which I have to thank the Biological Station at Plymouth, I found upon an alga that was thickly covered with Eudendrium album, Nutting, between the stalks of the Eudendrium a single specimen of the rare Halatractus (Corymorpha) nanus (Alder), which has until now been considered an Arctic species. The specimen is of special interest owing to the fact that this form has only been exceptionally met with in subarctic waters, and has only been recorded in England as a special rarity from the colder coast of Northumberland [Hincks, 1868; Allman, 1872; Pennington, 1885]. As far as can be gathered, it has only been found once even there. Its discovery now at Plymouth, on the warm southern coast washed by the Gulf Stream, is therefore the more surprising. In the comprehensive list of the Marine Fauna of Plymouth in this Journal (N.S., Vol. VII, pp. 155–298, 1904) the species is not included.

The following list is one of the results of my work during a stay of nearly four months at the Plymouth Laboratory of the Marine Biological Association. I desire to express my thanks to the Director and the Staff of the Laboratory for the interest they took in my work and for their kind assistance.

Colonies of Bowerbankia pustulosa, collected in July and August, 1911, in and near Plymouth Sound, contained a great many ovicells and produced numerous larvae, when kept in a flat glass trough and put under circulation during the night. The small yellowish larvae have a decidedly positive phototropism. They gather on the surface of the water on that side which is turned towards the light, from which position they sink to the bottom of the glass. Their movements slacken gradually in the course of a few hours, and at last are limited to revolving in a small circle until they fasten on the sides of the glass. Here they complete their metamorphosis, and in a few days the primary polypides are expanding their ciliated tentacles. The result was better when the just-hatched larvae were brought into a jar sterilised by hot water and filled with so-called outside water, i.e. water from beyond the Breakwater. This jar was fitted with a glass stand carrying a number of cover-glasses. When the larvae settled on these, it was easy to make total preparations of them without detaching them.

The American limpet, or slipper-limpet, known to naturalists as Crepidula fornicata, was introduced into England about 1880, being recorded at that time by Mr. B. S. Dodd in the Proceedings of the Malacological Society for 1893. Dodd, it is interesting to note, sounded even at that early time a warning note against the possible spread of this animal, and the probability of its becoming an enemy to the oyster farmer. There is no doubt that this limpet has been, and is probably still being introduced along with American oysters, on which it fixes itself. I have myself seen it unshipped along with oysters, but all the specimens I found had died recently. The spread of the limpet appears to have been very rapid on some grounds, as, for example, at West Mersea, where, since its appearance about eight years ago (from information obtained from local oyster fishermen), it has spread so that it is now more common than oysters.