OCR Text |
Show 1903.] MEDUSA FROM BRITISH COLUMBIA AND ALASKA. 183 tentacles are not rolled in and contracted, this Medusa is evidently a species of Mesonema. Great difficulty was found in preserving our specimens ; they seemed to become very brittle on short preservation by the ordinary method in formalin, the slightest shaking of the bottle in which they.were pres?rved causing them to break up into small fragments; the majority of our jars reached home with nothing but a mass of debris at the bottom. This Medusa was quite common about Victoria during July, and is evidently as abundant on the opposite shore of Puget Sound, being represented by numerous examples in Prof. Kincaid's collection from the vicinity of Port Townsend. When kept in captivity they can be readily observed opening the mouth widely right back to the commencement of the radial canals and then rapidly closing it again, wrapping the oral lobes into a corkscrew-shaped mass, as Haeckel (18) has represented the oral lobes in his plate of Polycanna fungina (pi. xiv. fig. 4). This may be repeated rapidly over and over again. Possessing about an equal number of radial canals and tentacles, this species comes under Haeckel's subgenus MesonemeUa, but is different from either of his two species M. eurystoma and M. cyaneum {Zygoclactyla cyanea of Agassiz). Nor does it agree with Fewkes's new species (13), M. bairdii, because in this there are four times as many radial canals as tentacles. C. TRACHOMEDUS^E. I. P ETAS ID M Haeckel. GONIONEMUS A. Agassiz. 1. GONIONEMUS VERTENS A. Agassiz. Specific description.-The bell is described by Agassiz as " an oblate spheroid cut in two by a plane passing through the north and south poles, the plane of intersection containing the circular tube." He also gave other features that will be embodied in this account. Preserved specimens are 1*75 cm. tall and 1*50 cm. broad, being about the same size during life. The bell is considerably taller than a hemisphere, is rather thin, and tinged a yellowish green during life. There is a slight conical depression in the roof of the stomach. The velum is well developed and rather broad stretching almost halfway across the opening of the subumbrellar cavity. The tentacles are twice the longest diameter of the bell in length, and look wiry and somewhat heavy for the size of the animal. They show the ringed welts of nematocyst well developed, standing out very prominently. There are no true tentacle-bulbs, the tapering ends of the tentacles being inserted directly in the bell-margin; but below their insertion there are rather large, oval brown basal papilla?. Some distance from the outer end of |