80 ZOOLOGY. 



dently, is called the columella, while the small separate pillars 

 between the columella and the septa are termed palulL In 

 the compound or tree-like corals, each young coral polyp 

 forms a calicle, theca, or limestone support of its own, which 

 unites with the other by calcification of the connecting sub- 

 stance of the common body. This intermediate layer is 

 termed cwnencliyma (Huxley). 



The simpler corals consist of but a single calicle contain- 

 ing one polyp, as in Flabellum, Deltocyathus, and Caryo- 

 pliyllia. They live free, fixed in the mud in deep water, 

 and occur in water with a temperature of about 32 Fahr. 

 Flabellum angular e Moseley has been dredged off Nova 

 Scotia in 1250 fathoms. 



Deltocyathus Agassizii, which is not uncommon in the 

 Florida channel, at depths varying from sixty to three hun- 

 dred and twenty-seven fathoms, has been dredged by us at the 

 mouth of Massachusetts Bay, in one hundred and forty fath- 

 oms (temperature 39 to 42 Fahr.). An allied form is 

 UlocyatUus arcticus Sars, said by Duncan to be the same as 

 Flabellum laciniatum Edwards and Haime, a fossil of the 

 late tertiary, dredged by us in one hundred and fifty fath- 

 oms, near St. George's Banks, Gulf of Maine. 



In the family of which Oculina, the eye-coral, is a type, 

 the polyp stock is compound, branched, increasing by lat- 

 eral buds. Lopkohelia prolifera Pallas (Fig. 53) occurs 

 in the seas of Norway, and has likewise been found to occur 

 on the banks off Nova Scotia and Newfoundland, while it 

 lives in the Florida Straits, in from 195 to 315 fathoms. 



In Mceandrina, or the brain-coral, Fama, Astraaantii As- 

 trangia, we have representatives of the important group 

 Astrceacca, in which the corallum is massive, more or less 

 hemispherical, and the polyp-cells or calicles are distinctly 

 lamello -radiate within, and generally so without. Budding 

 is usually carried on by division of the disks, or by spon- 

 taneous fission. In Mnssa the polyps are sometimes two 

 inches in breadth, as large as ordinary Actiniae. Diploria 

 cerebriformis Edwards and Haime is a brain-coral which is 

 common in the West Indies and at the Bermudas, some- 



