Invertebrate Gallery of the Indian Museum. 23 



and provided with a mouth surrounded by tentacles at the 

 other — the hollow of the tube forming the gastric cavity or 

 stomach. 



The gastric cavity is divided into compartments along 

 its whole length from pole to pole by radial partitions 

 formed by outstanding ridges of endoderm and mesoderm — 

 these being known as sarco-septa or mesenteric folds. 



2. CNIDARIA ANTHOZOA. 



[dases 4— X6, toith the cxaptiou of a ©itigle com^jartment ai 

 QTase 7 0aupii;li bu .SruphomtbusiC vtnl) €tenophora]. 



The Anthozoa comprise the Sea-anemones and various 

 kinds of Corals, and form a very large and important 

 group. They are all marine animals. The Corals especially 

 are of much interest, because they give rise by budding and 

 fission to great branching tree-like or turf-like colonies, 

 the massing together of which in the shallower waters of 

 tropical seas forms reefs of vast extent. These reefs often 

 become at places raised to the sea level, and they then 

 constitute the nuclei of groups of islands. Good examples 

 of such coral islands near at hand are the Laccadive and 

 Maldive Archipelagos. 



The Anthozoa are divided into two sub-Classes — the 

 Actiniomorpha and the Alcyoniomorpha. 



a. ANTHOZOA ACTINIOMORPHA. 

 The Actiniomorpha are divided into three Orders 

 Actiniaria, Antipatharia, Madreporaria. 



i. ANTHOZOA ACTINIOMORPHA ACTINIARIA. 

 [JEibile of (Ease 7]. 

 The type of simple Actiniomorph Anthozoan is the Sea- 

 anemone (Actinia), of which there are numerous examples 

 exhibited, both glass models and actual spirit specimens, 

 in Case 7. From an inspection of one of these it will be 

 seen that the sea-anemone consists of a tube usually 



