Page:The aquarium - an unveiling of the wonders of the deep sea.djvu/237

190 of alarm, real or supposed, it will suddenly close, and assume a distended globose appearance, with the oval mouth a little open, and filled with the clustering tentacles.

In colour the variety, though considerable, is restricted to certain limits easily defined. The most beautiful varieties that I have seen are the pure white, and the rich full orange or red-lead; but the more common states are cream-colour, flesh-colour, pale red, and olive. This last is perhaps the least pleasing hue, but there is considerable variation even here, for in some the tint approaches to a warm umber-brown, and in others becomes a dingy blackish olive. Generally speaking, the hue, whatever it be, is uniform in the same individual; but I possess specimens, of the umber-colour, in which the tentacles are almost white, imparting a peculiar speckled aspect to the disk; the crenated mouth in these is full orange.

The body is smooth, lubricated with mucus, and perfectly free from sucking glands. It forms at the summit of the column a thick rounded rim, sometimes everted, not in the least crenated, within which a deep groove exists around the exterior of the tentacular disk. The latter is membranous, expanded, and excessively puckered or frilled with broad and deep involutions, of which there are usually six or eight; the infoldings are sometimes simple, sometimes compound; in the latter case forming a semi-globose