1908. ANNANDALE, "Observations on specimens of _Hydra_ from Tibet, with notes on the distribution of the genus in Asia," Rec. Ind. Mus. ii, p. 311. 1910. POWELL, "Lessons in Practical Biology for Indian Students" (Bombay). 1910. LLOYD, "An Introduction to Biology for Students in India" (London). GLOSSARY OF TECHNICAL TERMS USED IN PART II. _Aboral_ (or _basal_) The disk by means of which a free polyp _disk_ attaches itself to external objects. _Cnidoblast_ The living cell of the nematocyst or nettle-cell (_q. v._). _Cnidocil_ A minute bristle that projects on the surface in connection with a nettle-cell (_q. v._). _Column_ The upright or potentially upright part of a polyp (_q. v._). _Ectoderm_ The external cell-layer of the body-wall. _Endoderm_ The internal cell-layer of the body-wall. _Green (chlorophyll) Minute green bodies contained in cells corpuscles_ of polyps or other animals and representing a stage in the life-history of an alga (_Chlorella_). _Mesogloea_ The intermediate, gelatinous layer of the body-wall. _Nettle-cell (nematocyst)_ A cell capsule full of liquid in which an eversible thread is coiled up. _Oral disk_ The eminence that surrounds the mouth and is surrounded by tentacles. _Peristome_ See "oral disk." _Polyp_ An individual coelenterate of simple structure that is fixed temporarily or permanently by one end of a more or less cylindrical body and possesses a mouth at the other end. _Tentacles_ Filamentous outgrowths (in _Hydra_ hollow) of the body-wall round the mouth. LIST OF THE INDIAN HYDRIDA. Class HYDROZOA. Order ELEUTHEROBLASTEA. Family HYDRIDÆ. Genus HYDRA, _Linné_ (1746). 24. _H. vulgaris_, Pallas (1766). 25. _H. oligactis_, Pallas (1766). Order ELEUTHEROBLASTEA. Naked hydrozoa which reproduce their kind by means of buds or eggs, or by fission, without exhibiting the phenomena of alternation of generations. Family HYDRIDÆ. HYDRAIDÆ, Johnston, Hist. Brit. Zooph. (ed. 2) i, p. 120 (1847). HYDRIDÆ, Hincks, Hist. Brit. Hydroid. Zooph. p. 309 (1868). Small Eleutheroblastea in which the mouth is surrounded by hollow tentacles. Permanent colonies are not formed, but reproduction by budding commonly takes place. Genus HYDRA, _Linné_. TYPE, _Hydra viridis_, Linné.