FAUNISTIC NOTES AT PLYMOUTH DURING 1893-4. 229 
Ciona intestinalis—September (and earlier ?). 
Clavelina lepadiformis.—June. 
Archidistoma aggregatum.—June. 
Morchellinm argus.—September (and earlier ?). 
Amarecium Nordmanni.—June. 
Pisces, 
Elasmobranchia, 
Scylliwm catulus—November, December, January. 
Scylliwm canicula.—December, January, February. 
Acanthias vulgaris.—January, February, March. 
Teleostet. 
Chiefly between January and June. 
III. Marerrats ror A CALENDAR OF THE FLoatinG Fauna. 
The floating fauna of the sea in the immediate neighbourhood of 
land is so largely composed of larval or other forms derived from 
the bottom fauna, and possessing in the majority of cases only a 
transitory pelagic existence, that, from the very nature of the case, 
the floating fauna assumes a highly periodical character, whose 
phases are directly dependent on the seasons of breeding, hatching, 
and metamorphosis of the animals living on the adjacent or under- 
lying tracts of submarine land. This fact alone invests the record- 
ing of such simple phenomena as the breeding seasons of marine 
animals, or their rates of growth and metamorphosis, with a high 
degree of interest and value; and in the days to come, when this 
fact has been sufficiently and practically appreciated, we shall make 
much more rapid progress in our knowledge of the bionomics of the 
sea. The dependence of the floating and the bottom faunas of our 
coasts upon each other is so intimate that it is impossible to separate 
the efficient study of the one from that of the other. A bottom-haunt- 
ing species no sooner attains its breeding or its hatching period than 
the floating fauna immediately receives a new addition to its numbers. 
For a longer or shorter period the larve in question lead a pelagic 
life, and then, sooner or later, sink once more to the bottom to 
undergo their final transformations. Seeing that every species 
has its own particular breeding season, which does not necessarily 
coincide with that of any other species, and that the duration of 
the pelagic stage is equally variable in different cases, it follows 
that there must be a perpetual change going on in the constitu- 
tion of the floating fauna in any one locality, an incessant rising 
to the surface of new forms just commencing their pelagic phase, 
