1872. KLEINENBERG, "Hydra. Eine Anatomisch Entwicklungsgeschichtliche Untersuchung."

1882. JICKELI, "Der Bau der Hydroidpolypen," Morph. Jahrb. viii, p. 373.

1887. NUSSBAUM, "Ueber die Theilbarkeit der lebendigen Materie. II.

Mittheilung. Beitrage zur Naturgeschichte des Genus Hydra," Arch. mikr.

Anat. Bonn, xxix, p. 265.

1891. BRAUER, "uber die Entwicklung von Hydra," Zeitschr. wiss. Zool.

Leipzig, lii, p. 169.

1892. CHUN, "Coelenterata (Hohlthiere)," in Bronn's Thier-Reichs II (2).

1905. DOWNING, "The spermatogenesis of Hydra," Zool. Jahrb. (Anat.) xxi, p. 379.

1908. BRAUER, "Die Benennung und Unterscheidung der Hydra-Arten," Zool.

Ann. x.x.xiii, p. 790.

1909. FRISCHHOLZ, "Biologie und Systematik im Genus Hydra," Braun's Annal. Zool. (Wurzburg) iii, p. 105.

1910. BERNINGER, "uber Einwirkung des Hungers auf Hydra," Zool. Anz.

x.x.xvi, p. 271.

(b) _Asiatic References._

1894. RICHARD, "Sur quelques Animaux inferieurs des eaux douces du Tonkin (Protozoaires, Rotiferes, Entomostraces)," Mem. Soc. zool.

France, vii, p. 237.

1904. VON DADAY, "Mikroskopische Susswa.s.serthiere aus Turkestan," Zool.

Jahrb. (Syst.) xix, p. 469.

1906. ANNANDALE, "Notes on the Freshwater Fauna of India. No. IV. _Hydra orientalis_ and its bionomical relations with other Invertebrates," J.

Asiat. Soc. Bengal (new series), ii, p. 109.

1906. ANNANDALE, "The Common _Hydra_ of Bengal: its Systematic Position and Life History," Mem. As. Soc. Bengal, i, p. 339.

1907. ANNANDALE, "Notes on the Freshwater Fauna of India. No. X. _Hydra orientalis_ during the Rains," J. Asiat. Soc. Bengal (new series), iii, p. 27.

1907. ANNANDALE, "Notes on the Freshwater Fauna of India. No. XI.

Preliminary Note on the occurrence of a Medusa (_Irene ceylonensis_, Browne) in a brackish pool in the Ganges Delta and on the Hydroid Stage of the species," J. Asiat. Soc. Bengal (new series), iii, p. 79.

1907. WILLEY, "Freshwater Sponge and Hydra in Ceylon," Spolia Zeylan.

Colombo, iv, p. 184.

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.

Cla.s.s HYDROZOA.

Order ELEUTHEROBLASTEA.

Family HYDRIDae.

Genus HYDRA, _Linne_ (1746).

24. _H. vulgaris_, Pallas (1766).