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Show 166 MESSRS. L. MURBACH AND C. SnEARER O N [June 16, make certain of this in sections. No medusa-buds were observed, although they were sought for in a large number of individuals. In sections, the lumen of the stomach-cavity is seen to be quadrangular (PI. XXII. fig. 5). In some examples the approximation of the stomach-walls forces out the corners of this quadrangle, so that they are thrown into folds something like the condition described by Linko (25) in Sarsia brachygaster. Colour.-Bell-margin and radial canals pale blue, proboscis reddish violet or light purple. Ocelli black. Habitat.-Victoria Harbour, Puget Sound, collected by Shearer. Discussion.-This Medusa is perhaps the commonest species in the waters of Puget Sound during the month of July. It was seen every day in great numbers, frequently the shoals or banks in places so dense as to obscure the colour of the water. The Medusa? allow themselves to drift passively in the tidal currents, once in a while making a few vigorous contractions of the bell, then remaining quiet as before. While being carried along in this manner, their tentacles are extended a considerable length behind them, one individual having been noticed with its tentacles extended a distance of over 9 cm., although its bell measured less than one centimetre in height. When suddenly taken up from the surface of the sea with their tentacles in the extended condition, they contract them quite slowly and with an irregular jerky motion, the animals taking two or three minutes to contract them to the normal length. The size and length of the proboscis and stomach in the Codonicla? seem to be subject to great variation ; this is markedly the case in this species, in which it varies from a short stump several millimetres long to a condition in which the stomach protrudes almost beyond the velum. One individual of C. api-culum, kept for several days in a small jar of sea-water, had a habit of resting about half a centimetre from the bottom of the jar, allowing its proboscis to drop down every now and again. As soon as this touched the bottom it was rapidly withdrawn into the bell, and then slowly allowed to drop down again. Many examples of this Medusa which have been preserved in formalin show interradial contractions of the bell-surface, giving it a cubical appearance; these contractions are not present in the living condition, and are caused by preservation. It may be contractions similar to these which Hincks (22) mentions as interradial on the bell of Sarsia {Codonium) pulchella, and which Haeckel calls " interradial furrows" in the same species. The examination of a large number of individuals shows considerable variation both in the size of the bell, the shape of the apical canal, the general shape of the proboscis, and in the length of tentacles. Apart from these variations, its specific distinctive characters would seem to be: the truncate shape of the bell; the small apical process on the exumbrella; the short pointed apical canal, which is never knob-shaped ; the |