CORAL POLYPS. 



79 



lives in deeper water. Its young, however, is at an early 

 «tage of its existence a free-swimming polyp, which was 

 originally described as an adult animal under the name of 

 Arachnactis. In Zoantlius the tegument is tough and 

 leathery, and the diSerent polyps are con- 

 nected by stolons. Epizoantlius americanus 

 Verrill lives in deep water, off the coast of 

 New Jersey and Southern New England, in 

 about twenty fathoms. Cerimithus, a gigantic 

 ^orm, a native species of which (C. borealis 

 Verrill) lives at the depth of one hundred 

 fathoms in the Gulf of Maine deeply sunken 

 in the mud, where it secretes a shiny leathery 

 tube, is perforated at the end of the body ; 

 the young of a corresponding European 

 species is also free- swimming, like the youug 

 Edwardsia. 



The coral polyjis differ from the Actinoids 

 in secreting in the mesoderm a limestone 

 base, from which arise in the Zoantharian 

 corals stony septa serving as a support to the 

 animal ; these septa are deposited or secreted 

 in the chambers, so that in the coral polyp 

 ihere are soft partitions alternating with the 

 limestone ones, the latter formed at the base 

 ■of the polyp, not completely filling the inter- 

 mesenterial chambers. 



Order 1. Zoaniliaria. — We will now enumerate some of 

 "the leading forms of the first order of Anthozoa, the Zoan- 

 iliaria, to which the sea-anemones and most of the stony 

 corals belong. The group is called by some recent authors 

 Hexacoralla, the number of primary chambers and tenta- 

 cles being six, the latter rounded, conical, or filiform. In 

 the simple cup-shaped corals, as Deltocyatlms and Caryo- 

 pTiyllia, the coral forms a cup or tlieca, the lamellae which 

 arise from the base terminate in as many septa, the spaces 

 between which are termed loculi. A central pillar or col- 

 Timn formed by the union of the septa, or arising indepen- 



Fig. 52. — Bal- 

 camjia producta. 

 — After verrill. 



