.364 



MEDUS.E OF THE WORLD. 



Limnocodium victoria (sowerbii), Allman, 1880, Journ. Linnean Soc. London, vol. 15, p. 131, figs. 



Limnocodium sowerbii (hydroid), Bourne, 1884, Proc. Roy. Soc. London, vol. 38, p. 9. 



Limnocodium, sp., Romanes, 1885, Jelly-fish, Star-fish, and Sea-urchins, p. 242, fig. 31. 



Limnocodium sowerby i, Fowler, 1S90, Quart. Jour. Micros. Sci. London, vol. 30, p. 507, plate 33 (hydroid, development of 



medusa, and references to previous literature). 

 Limnocodium, sp., Lankester, Minchin, Fowler, and Bourne, 1900, Treatise on Zool., Part 2, Hydromedusie, p. 47. 

 Limnocodium , Boecker, 1905, Biol. Centralbl., Bd. 25, p. 605 (found at Munchen, Bavaria).— Cremer, 1907, Sitsungsber. 



Gesell. Morph. Phys., Munchen, Bd. 22, p. 41. 



This interesting medusa was first found by Mr. Sowerby during 1880 in the tresh-water 

 tank devoted to the cultivation of the large waterlily, Victoria regia, in Regent's Park, London. 

 The temperature of the water was 86° to 90 F. It has since then been introduced into other 

 waterlily tanks in England, France, Germany, and the United States. It feeds upon Daphnia, 

 and was probably introduced from South America or the West Indies. Mr. Sowerby presented 

 specimens of the medusa to Allman and Lankester, who described them. 



Adult medusa. — Bell nearly hemispherical, about 12 mm. wide. Gelatinous substance 

 quite thin. Nearly 200 marginal tentacles, of various sizes, the oldest being the largest; these 

 tentacles project at various levels from the sides of bell, slightly above margin. The 4 largest 

 (perradial) tentacles project from the sides of the bell at some distance above the margin. 

 Projecting from a zone lower down, nearer the margin, are about 28 or more tentacles of 

 medium sizes, and lowest of all is a third set of about 192 or more small tentacles. The 

 entodermal cores of these tentacles are hollow and their ectoderm bears prominent nemato- 



cyst-warts at fairly regular intervals. The largest 

 tentacles are usually somewhat longer than bell- 

 diameter, but all are highly contractile. They taper 

 gradually from base to tip and lack suckers or other 

 appendages. No ocelli. 



There are about 128 lithocyst-organs scattered 

 somewhat irregularly between the tentacles. Each 

 of these organs is composed of an ovoid cluster of 

 entodermal cells on the inner (velar) side of the 

 ring-canal. This ovoid "otolith" is suspended by 

 means of a short, narrow stalk and is contained in 

 ijlr\^ !l ' an elongate, pyriform, closed capsule within the 

 gelatinous substance of the velum. This capsule 

 is lined with thin, ectodermal epithelium which 

 also incases the ball-like mass of entodermal cells 

 constituting the "otolith." Velum is thick and 

 gelatinous; the large, elongate, closed lithocyst cav- 

 ities project centripetally into its gelatinous sub- 

 stance. 4 narrow, straight radial-canals and a 

 Fib. lOT.-Craspedacusta sowerbii, after Allman. nlar(r j na i nn( T-canal without centripetal diverticula. 



• • • 1 ■ 1 



This ring-canal is quite wide and pursues a sinuous course around the margin, rising highest 

 at the points of origin of the largest tentacles. The manubrium is prismatic below, tubular 

 above, and projects for about half its length beyond velar opening. 4 large lips with folded, 

 crenated edges. 4 sac-shaped gonads arise from the 4 radial-canals, somewhat nearer to 

 radial corners of stomach than to bell-margin. Only male medusae have been observed. 



Entoderm of manubrium, gonads, and bell-margin brownish-yellow, other parts colorless. 



Hydroid.— That which is probably the hydroid of this medusa was first found by Parsons, 

 1880, and first described by Bourne, 1884. It grows in colonies of 2 or 3 polypites arising from 

 common base and is attached to the under sides of leaves, etc., floating or growing in the 

 water of the lily-tank in Regent's Park. The polypites are only about 0.6 mm. long and are 

 cylindrical with rounded peristomes devoid of tentacles. The mouth is a simple terminal 

 opening. There is no perisarc, but the sides and bases of the polypites are incased in a coating 

 of sticks, detritus, etc., caught apparently in slime. The oral ends are, however, free from 

 this detritus. Planula-shaped buds are produced upon the basal halves of the sides of the 

 polypites, and these are set free and settle down to form new colonies of hydroids, very much 

 as in Microhydra ryderi. The medusa-bud is produced at the oral end of the polypite, both 



