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PROCEEDINGS OF THE 



[April, 1857. 



rently being a branching polyp-body, whose many mouths are 

 each surrounded by a circle of tentacula. The medusa buds are 

 developed indifferently at any point along the branching stem, 

 and since the polyp has the faculty of contracting its tentacula 

 like Hydractinia, the medusa buds growing near the extremity of 

 a stem, sometimes appear to be unconnected with any hydra-like 

 polyp. The tentacula of the medusa are developed in the involute 

 manner, like those of Sarsia, and unlike the tentacula of Nemopsis, 

 which, as described, are developed in the evolute or external man- 

 ner, like those of Corynitis. When very young the medusa's bell 

 is, as usual, thin, increasing to the great thickness of the same, or- 

 gan in the adult, as the animal grows older. The digestive cavity 

 is small and the oral cirrhi are at first simple, and as they grow first 

 bifurcate and afterwards repeat this until the specific character of 

 the cirrhi is acquired. The number of tentacula to each bulb at 

 the time of the medusa's liberation is probably two or three in 

 most cases, but I have found a specimen (PI. 10. fig. 10) fully 

 representing the genus Cytaeis, having besides the simple oral 

 cirrhi only a single tentaculum to each bulb. 



Distribution. — Harbors of Boston and Charleston. 



HIPPOCRENE CAROLINENSIS, nov. spec. 

 PI. 10. ff. 8-10. 



In general form this species approaches more nearly the H. 

 superciliaris Agass. than either of the species described by 

 Forbes. It varies slightly from a nearly globular form to one a 

 little more elongated and oval. The largest specimens are usually 

 the more globular. The marginal bulbs give origin to but six or 

 eight tentacula each, at the base of each of which, on the under 

 side, is a very small black ocellus. The tentacula are of medium 

 length and usually carried tightly curled, at the ends, one pair of 

 each tuft borne quite stiffly upwards on the outside of the disk, 

 and another pair turned within the cavity of the bell. The digest- 

 ive trunk is quite elongate for Hippocrenidse, though it appears 

 to possess much contractility only in that part below the sexual 

 glands. The trunks of the males have usually appeared rather 

 longer than those of females. The oral tentacula are quite short 

 and with very few branches, bifurcating only twice or thrice, 

 and are never conspicuous. In some specimens the radiate tubes 

 present an arched outline in passing the top of the bell-cavity, 



