. Elementary text-book of zoology. HYDATINA. 151 III.âHYDATINA. Phylum ROTIFERA. Hydatina senta is a small microscopic animal very commonly found in freshwater ponds and streams. Its body is transparent and elongated. At the blunt or oral end is a ciliated funnel-like depression, the â vestibule, at the bottom of which is the mouth. The edge of the vestibule is fringed with a band consisting of specially long cilia, which is known as the cingulum. Further towards the centre of the vestibule is a broken row of Fig. 85.âVentral View of Hydatina Senta x 40. (After Plate). Trochus. (Esophagus. Rig
. Elementary text-book of zoology. HYDATINA. 151 III.âHYDATINA. Phylum ROTIFERA. Hydatina senta is a small microscopic animal very commonly found in freshwater ponds and streams. Its body is transparent and elongated. At the blunt or oral end is a ciliated funnel-like depression, the â vestibule, at the bottom of which is the mouth. The edge of the vestibule is fringed with a band consisting of specially long cilia, which is known as the cingulum. Further towards the centre of the vestibule is a broken row of Fig. 85.âVentral View of Hydatina Senta x 40. (After Plate). Trochus. (Esophagus. Right Hepatic Gland. Excretory. Tubule. Cingulum. longer cilia, called the trochus, whilst the groove between trochus and cingulum is raised into several lobes bear- ing styles. This com- plex apparatus is often called the wreath and serves for locomotion and for ingestion of food. The aboral end is tapering and termin- ates in a bilobed foot endowed witli a pair of adhesive glands. The body is enveloped in a thin delicate cuticle covering a simple ecto- derm. The mouth leads into a viastax which is a complex grinding apparatus containing chitinous teeth. From this an oesophagus is continued into a large digestive stomach fol- lowed by an intestine. The intestine terminates in an anus, situated not at the aboral end but on one surface, usually termed dorsal. Two salivary glands open into the mastax,' and two hepatic or^ digestive glands discharge their fluid into the stomach. The alimentary canal hangs freely in the cavity of the body, which is filled with colourless fluid. This body-cavity is traversed by connec- tive tissue and muscle fibres, but has no coelomic lining. Throughout its course, laterally to the alimentary canal, is a pair of excretory tubules which bear branches terminating in closed flame-cell sacs. Each tubule opens behind into the urinary bladder with a single aperture to the exterior near the anus, forming a cloaca. Anteriorly the two tubules Ovary. Yolk Gl
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