Page:The Zoologist, 4th series, vol 3 (1899).djvu/494

464 fetched this comparision between the two localities may seem at first sight, everyone who has had an opportunity of thoroughly observing the characteristic forms of vegetable and animal life in woods, and at the bottom of the sea, will inevitably be convinced of its accuracy. Again, in primitive plant life (Thallophyta), in the family Caulerpaceæ, "the genus Caulerpa contains nearly one hundred species, which present the most varied external forms, simulating those of many of the higher plants, such as Mosses, Ferns, Mare's-tails, Cactuses, Conifers, &c." It has been suggested that some of the seeds of Euphorbiaceæ, notably those of the Castor-oil plant (Ricinus), resemble beetles, and, as such, may be mistaken by birds and carried a small distance before being dropped. This seems very doubtful. Ricinus seeds and those of Para Rubber (Hevea braziliensis), which resemble them on a large scale, are ejected explosively from their capsules to a distance quite sufficient for their dispersal, and falling, as they constantly do, among the herbage, would certainly escape most insect-eating birds.

Fishes of the family Pomacentridæ, belonging to the spiny-finned division, which frequent the neighbourhood of coral reefs and islands, and thus closely resemble the scaly-finned fishes, Chætodonts, in their mode of life, also are very similarly and beautifully coloured. But in the opinion of Dr. Günther this is one of many instances showing that the colouration is due to a great extent to "the agencies of climate, of the surroundings, and of the habits of animals."

Another and very important distinction to be drawn when dealing with instances of mimicry and protective resemblance is one long since pointed out by Kirby and Spence, and one that demands the utmost consideration. To use the words of the teleological authors of the immortal 'Introduction to Entomology,' there are Passive means of defence, such as are independent of any efforts of the insect; and Active means of defence, such as