. The Biological bulletin. Biology; Zoology; Marine biology. A FEW CCELENTERATES OF WOODS HOLL. 107 devoid of definite perisarc. (This may be due in part to the habitat, on the crab, these animals being given to decorating themselves with various living organisms, such as hydroids, polyzoa, algae, etc., and if this hydroid were there by such process its very short stem devoid of perisarc may be due to its recent transplantation.) The hydranth is rather large, with two whorls of ten- tacles, the basal series about twenty- four in number, long, and filamentous, much as in Tubularia; oral tentacl
. The Biological bulletin. Biology; Zoology; Marine biology. A FEW CCELENTERATES OF WOODS HOLL. 107 devoid of definite perisarc. (This may be due in part to the habitat, on the crab, these animals being given to decorating themselves with various living organisms, such as hydroids, polyzoa, algae, etc., and if this hydroid were there by such process its very short stem devoid of perisarc may be due to its recent transplantation.) The hydranth is rather large, with two whorls of ten- tacles, the basal series about twenty- four in number, long, and filamentous, much as in Tubularia; oral tentacles few and short, about ten or twelve, apparently in two series, one very short, merely bud-like. Hypostome of hydranth rather cylindrical, entire hydranth low vasiform, and with defi- Fig. 9. nite constriction below the body. Medusa-buds borne on body of hydranth in series of racemose clusters, as shown in Fig. 9. Growth of medusas apparently rapid, the older forming the terminal portion of the cluster Color of hydranth pinkish red, tentacles paler. Medusa. — Bell transparent, subspherical or when older ob- lately spheroidal; diameter when first liberated about .5 to .6 mm., and becoming but little larger after several days in the laboratory, Walls of bell rather delicate, though not flabby ; velum very delicate, with tendency to evert during contraction. Radial canals four, rather open showing free movement of circulating fluid. Tentacles four, rather short, and terminating in knob-like masses of nematocysts, body of tentacles with nematocysts in scattered clusters of four to six in number usually, though some specimens seemed all but devoid of them. The entire exum- brella of newly-born medusae is more or less dotted with clusters of nematocysts. A characteristic feature of the medusa is the presence of eight rows of nematocysts arching over the exum- brella from the basal bulb of each tentacle, a row on either side. Basal bulbs rather prominent, and with scattered granule
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectb, booksubjectzoology
