38 CORALS 



cyaf/iits ciU'dtiis were obtained a little while ago attached 

 to the telegraph cable in the Persian dulf. In form they 

 are not unhke the Caryophyllias, but of a larger size, having 

 diameter of half an inch or more at the margin. 



When the coral is carefully studied, however, many 

 features can be noticed in which this coral differs from 

 Carvophyllia. These may be referred to here as an example 

 of the kind of characters that can be used for separating 

 genera and for the identification of specimens. 



There is a broad base of attachment as in Carvophyllia 

 which adapts itself to the surface of the support. Outside 

 the cup the costae may be seen extending from the base 

 upwards as delicate ridges. They are not, therefore, 

 covered up by a chalky " Epitheca " at the base as they are 

 in Caryophyllia. The septa are very numerous and covered 

 with minute granulations arranged in a series of longitudinal 

 and radial row^s, in contrast to the smooth septa of Caryo- 

 phyllia. The inner margins of the septa exhibit a number 

 of large nodules which represent the pali, and these pass 

 imperceptibh' into the central depressed columella, which 

 is similarly covered with nodules. In Caryophyllia the pali 

 and the columella are quite distinct. Such a technical 

 description is difficult to follow unless the specimens are in 

 the hand, but sufficient has been said, perhaps, to indicate 

 that differences in structure such as these, when found to 

 be constant in a large number of specimens of both corals, 

 are sufficient to justify their separation as distinct genera. 



Paracyathus cavatiis is also found in the Indian Ocean, 

 and other species of the genus are found in the Mediterranean 

 Sea and elsewhere. 



Heterocyathus. — The genus Heterocyathus presents 

 us with some features of special interest. It is a small coral 

 about one-third of an inch in height which is found in large 

 numbers at depths of 20-40 fathoms of water off the coast 

 of Natal, in the Persian Gulf, and other localities in the 

 Indian Ocean. An important difference between this coral 

 and those belonging to the family that has been described 

 is, that the free edges of some of the septa meet and fuse, 

 forming triangular chambers in which septa of a lower 



