Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 FIG. 260.—Young Diplozoon (after B. Zeller). a, Two young Diporpa beginning to attach themselves together, b, After both individuals have attached themselves. O, mouth; //, fixing apparatus; Z, papilla?; G, sucker. only becomes sexually mature after three and more years. In some exceptional cases, and always when the larva has passed on to the gills of a very young tadpole, it becomes sexually mature in the branchial cavity of the latter. The forms then remain very small, are without the
Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 FIG. 260.—Young Diplozoon (after B. Zeller). a, Two young Diporpa beginning to attach themselves together, b, After both individuals have attached themselves. O, mouth; //, fixing apparatus; Z, papilla?; G, sucker. only becomes sexually mature after three and more years. In some exceptional cases, and always when the larva has passed on to the gills of a very young tadpole, it becomes sexually mature in the branchial cavity of the latter. The forms then remain very small, are without the copulatory canals and uterus, and die after the production of a single egg, without ever getting to the bladder. a FIG. 261 .-Egg (a) and larva (b) of E. Zeller). Fam. Polystomidse. With seve- ral posterior suckers, which are usually paired and arranged in two lateral rows, and are rein- forced by an armature of hooks. The genital openings are fre- (after quently surrounded by hooks. Many species have a length of only a few lines. Polystomum Zed., with four eyes ; with no lateral suckers at the anterior end, but with oral sucker; with six suckers, two large median hooks and sixteen small hooks at the posterior end. P. integerrimum Rud., in the bladder of Jtana tniijjtn'ai-ia. P. occllittum in the pharyngcal cavity of Einys. In the formation of the testis and the absence of the uterus it resembles the adult form of P. integerrimum from the branchial cavity of thetadpole. OctdbotTirium laneeolatum Duj. Onohocotyleagypendioulata Kuhn, on the gills of Elasmobranchs. Diplozoon v. Nordm. The animal is double, two individuals being fused to
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