The observations which form the subject of the following notes deal with only part of the total material on which my studies of teleostean reproduction, pursued during the last two years, have been made; but as the other and larger part of the material consists of preserved specimens of the young (chiefly post-larval) stages of fishes collected during the four years 1906 to 1909 inclusive, it is more convenient to deal with the egg collections of the past year first and to treat the whole collection of young fry separately in a further paper.

The investigations in the American Tropics described in this paper were made during the summers of 1911 and 1912 under the auspices of the Carnegie Institution of Washington: the work was made possible by the invaluable help and kindness of Dr. Alfred G. Mayer, Director of the Department of Marine Biology. The investigations in Temperate waters were made from the Plymouth Laboratory of the Marine Biological Association of the United Kingdom, and my thanks are due to the Council and Director of the Association for giving me every facility for the work.

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.

This paper is a preliminary account of a series of experiments on the hybridization of Echinoids, first commenced by one of our number (De Morgan) at Plymouth in 1909, and which will form part of a larger work now approaching completion. This will comprise the hybridization of Echinus acutus, E. esculentus, and E. miliaris, together with an account of the cytology of the hybrid crosses and the control of paternal and maternal influence by chemical means.

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.

In the past, deep-sea water samples for bacteriological purposes have been taken either by means of water-bottles provided with taps, and so made that the sample came in contact with metal, or in evacuated sterilized glass vessels drawn out to a fine point and sealed in the flame. The water-bottle is difficult to sterilize on account of the taps, and the results obtained are vitiated by the bactericidal action of metals. The sealed glass tube is free from these defects, but at even moderate depths it is liable to collapse on the sudden change of pressure when the end of the capillary portion is broken off.

It is generally conceded that the plankton of tropical and sub-tropical seas is far less in quantity than that found in colder waters.

The zoö-plankton depends ultimately for its food on the phyto-plankton; hence any factor limiting the growth of the phyto-plankton, which is capable of functioning in tropical and not in temperate or Arctic waters, might offer an explanation of this phenomenon. It has been shown by various investigators that this factor is not temperature, light, or salinity, and it has been suggested that the explanation may lie in the relative deficiency in tropical seas of the nitrates or nitrogenous compounds which are so essential for all plant life. A matter of common observation in support of this view is the remarkable scarcity of algal growth in the shallow waters of tropical shores as compared with that in similar situations in temperate regions, and the fact that in the tropics, wherever sewage or other nitrogenous waste is poured into the sea, a free growth of algæ is found.

A Synopsis of the Aphroditidre of the English Channel by Mr. T. V. Hodgson is given in the Journal Marine Biological Association, Vol. VI, No. 2, 1900.

APhrodita aculeata, Lin. McIntosh, Mon. Brit. Ann., Vol. II, p. 247.

The group of primitive Annelids Dinophilus comprises some eight or nine species. They are remarkable for the fact that some show a well marked sexual dimorphism, in which the male is rudimentary, without any mouth or digestive tract, while in others the sexes are the same size and exhibit no signs of this dimorphism. The group as a class, therefore, is readily divisible into two subdivisions, in one of which all the species are sexually dimorphic, unpigmented, while in the other they are highly pigmented, a bright red, and are sexually monomorphic. The former may be called the Leu-codinophilidae, while the latter may be called the Erythrodinophilidae.

My thanks are due to Dr. Allen for permitting me to examine this collection.

In all 292 specimens were obtained, but of these 16 were young immature Asteroidea and Echinoidea. It is impossible to identify these with any degree of certainty, and I have not hazarded an opinion about them.

The remainder belong to 17 genera and 24 species. The Ophiuroidea were particularly numerous, 190 specimens belonging to that class.

The classification followed is that of Professor MacBride in the Cambridge Natural History.

In 1908 Sir Charles Eliot published in the Journ. Mar. Biol. Assoc., Vol. VIII, No. 3, a paper “On the Genus Cumanotus”; in that paper he showed that Coryphella beaumonti, discovered and named by him in 1906, was to be referred to the above genus, which had been first established by myself in 1907 from a study of the Norwegian C. laticeps, described at the same time as a new species.

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 table is merely intended as a rough classification of eight of the most common species of bacteria found in the Laboratory Tanks. Only the forms which occur free in the water in the greatest numbers have been considered, and the moulds and higher bacteria which can be cultivated from scrapings from the walls of the tanks have not been included.

In his Report on the Actiniaria of the Norwegian North-Atlantic Expedition, D. C. Danielssen erected the genus Kodioides to receive the remarkable form which he named K. pedunculata, a single specimen of which was dredged at Station 35, July 5th, 1876, in 1050 fathoms, Lat. 63° 17′ N., Long. 1° 27′ W., the bottom being Biloculina Clay. The detailed description will be found in the section “Actinida,” Vol. V, pp. 77–82, PI. VI, Tigs. 3–4; XXII, 8–11; and XXIII, 1–4. The genus is there characterized as follows: “The body encrusted, piriform, with a long bare stem terminating in a pedal disc. Two series, containing a few retractile tentacles. 12 pairs of septa, of which 6 pairs perfect. Suckers on the encrusted portion of the body. No gullet-groove. Mesodermal, annular muscles. Acontia.”

The Gammarus here described is found in Chelson Meadow, a large tract of reclaimed land lying near the mouth of the Plym, and protected from the tidal water by an embankment. The land is drained by ditches, which empty into the Plym at low water by means of sluice-gates. The sea-water enters in volume only at the highest tides over the top of the sluice-gates, but there is a constant slight infiltration of salt water through the embankment.

The present paper is the outcome of an investigation made on a species of Gammarus inhabiting both fresh and brackish water (4, p. 657). As this species (G. zaddachi) seemed to show a marked variation in appearance according to its environment, we instituted experiments in the Laboratory at Plymouth on G. chevreuxi to see if a similar variation in appearance could be brought about by varying the degree of salinity of the water in which the animals lived.

The larva of Nephthys was originally described by Claparède and Mecznikow (2) in 1868, from specimens obtained from the Plankton at Naples. Since then it has been figured by Fewkes (3), Häcker (5), and Gravely (4). The larva of Glycera is, as far as I am aware, hitherto undescribed.

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.

Four ordinary meetings and one special meeting of the Council have been held during the year at which the average attendance has been thirteen. A Committee of the Council visited and inspected the Plymouth Laboratory.

The Council desire to express their thanks to the Councils of the Royal Society and of the Linnean Society, in whose rooms their meetings have been held.