136 



ZOOLOGY 



SECT. 



Clathrozoon, an Australian genus, resembles it in having branched 

 and intertwined coenosarcal tubes, the perisarc of which under- 



FIG. 94. Hydra. A, vertical section of entire animal ; B, portion of transverse section, highly 

 magnified ; C, two large ectoderm cells ; D, endoderm cell of H. viridis ; E, large nematocyst ; 

 F, small nematocyst ; G, sperm ; a, ingested diatom ; ltd. 1, bd. 2, buds ; chr. chromatophores ; 

 xaW. cnidoblast ; cnc. cnidocil ; ect. ectoderm ; end. endoderm- ; ent. cav. enteric cavity ; ent. 

 cav. Its prolongation into the tentacles ; fl. flagellum ; hyp. hypostome or manubrium ; int. c. 

 interstitial cells ; m. pr. muscle processes ; mth. mouth ; msgl. mesogloea ; ntc. large, and ntc'. 

 small nematocysts; nu. nucleus; ov. ovum; ovy. ovary ; psd. pseudopods ; spy. -spermary, 

 vac. vacuole. 



goes fusion, but the complex mass thus produced, instead of 

 forming an incrustation on a shell, is a large, abundantly branched, 



