188 Miscellaneous. 



they are also not quite transparent, but coloured sulphur-yellow at 

 the margin, though colourless elsewhere. 



The creature as it tloats and rests in the water has the shape of a 

 Koman T; the unpaired limb is band-shaped in transverse section 

 and thickened into a knob at the free end. In the latter is to be 

 noticed a yellow opaque body which, when examined under the 

 microscope, proves to be a Dlstomiim, usually doubled up, lying in a 

 cavity of the knobbed end, which is beset with rings of papillae. 

 The paired limbs of theT constitute leaf-shaped movable appendages. 

 Others of these " sporocysts" rest on the bottom of the vessel, lying 

 on the broad side, with the forks of the tail closed or open. The 

 whole assemblage usually rises all at once from the bottom and 

 swims actively about in the water, in the way that our gnat-larva3 

 do, afterwards floating again in the water — with the knobbed end 

 downwards — or sinking slowly to the bottom. 



As 1 had collected various species of snails in the same receptacle, 

 my first task was to separate them, and I soon ascertained that our 

 " free-swimming sporocysts" are developed from Linnueiis pfdustris, 

 var. corviis. Among fourteen specimens of this species one proved 

 to be infected with transparent sporocysts (four others with redite) 

 measuring as much as 2 millim.* in length, in which, as was soon 

 evident, our " free-swimming sporocysts " arise. Yet we have not 

 to deal with this stage, but rather with gigantic Cercaria; with 

 forked tails, the bodies of which, the future Distomuyn, exhibit the 

 usual relations, so long as the Cercarite are enclosed in the sporo- 

 cyst which produces them. After the escape the body becomes 

 retracted into a cavity which was previously distinguishable in the 

 swollen commencement of the tail, and remains in this condition. 



These ostensible " free-swimming sporocysts "' are therefore enor- 

 mously developed Cercaria^, and resemble Cercaria macrocerca and 

 C. cj/stojihora, except that they are a furcocercous form. 



Unfortunately my endeavours at rearing the Distomton by feeding 

 some goldfish with it, which in a few minutes had devoured over a 

 dozen Ccrcarirc, were not successful ; I could not rediscover the 

 flukes either in the intestine, the muscles, or the eyes, I intend, if 

 I obtain some more fresh material, to repeat the experiments with 

 other fish, since a direct development, i. e. with the omission of a 

 second intermediate host, is very probable ; possibly birds also may 

 play the part of final hosts. 



Until the question of the species is decided, the Cercaria may 

 stand as Cercaria mirnhUis. — Zoolorjisclwr Auziii/cr. xiv. Jahrg., 

 18U1, no. 375, pp. 308, 3GU. 



* [The ongiual has "cm." — Traxsl.] 



