4 
CEETACEOUS COEALS OR ANTIIOZOA 
cycles. They are either all equal and form a single row, or coronet, or unequal, 
forming two or more coronets. If only one coronet of pali is present, it exists 
opposite the septa of the penultimate cycle ; if there are two coronets, they are 
placed opposite the penultimate and antepenultimate cycles, and so on. 
The septa are on the upper edges either entire, or granular, serrated or dentate ; 
laterally they arc granular or spinulose. They are, however, not in all cases 
regularly developed. Sometimes one or the other of the primaries become obsolete 
or smaller ; in other cases two or four of the secondaries become equal to the pri- 
maries ; and in such cases wc have ajoparently 3, 4, 6, 8 or 10 systems instead of six. 
All these characters referring to the scleroderma, — the presence or absence of 
an exothcca, of dissepiments or synapticulm, or of pali, the number of systems, 
cycles and orders of septa, and whether their upper edge is entire or not, etc., — are 
of the greatest systematic importance. 
In the compound coralla the single individuums are more or less closely con- 
nected with each other by the coenenchyma, which is solid or porose, cellular or 
lamellar. Its development depends upon the manner of more or less perfect gem- 
mation of the coralla. 
I have already observed that all the Anthozoa are inhabitants of sea or brackish 
water. They are distributed in all latitudes, hut, as usually, are more numerous in 
troiiical than in cold seas ; the reef-building corals are restricted to the former seas. 
Comparatively only a small number of species, mostly the single coralla, live 
in great depths of the sea ; as a rule, they do not extend beyond about 20 fathoms, 
and generally they prosper best where the water is clearest and most agitated by 
atmospheric influence. On the large reefs only the upper layers to the extent of 
one or two feet are occupied by living individuums. Eor the study of the character 
and extent of the various coral reefs and their imjiortance to the geologist, I must 
refer the reader to the works of Darwin and Dana. It is sufficient to say that the 
knowledge of the fossil coral fauna is no less important for the determination of 
the age of geological strata than that of any other group of animals. The simple 
fact that whole genera and families of corals have become almost entirely extinct 
indicates the necessity of their fossil remains for the systematic zoologist. 
The classification of the Anthozoa is by no means so easy as their simple 
organisation might indicate, and there is considerable disagreement between various 
authors even as regards the first principles which ought to bo adopted. Eor om* 
purpose, it will, I think, be sufficient if I give a sketch of the first few divisions 
according to Bronn, his arrangement being only slightly modified from that of 
Messrs. Milne-Edwards and Haime. 
Bronn, paying more regard to the mode of multiplication than to the number 
of tentacles and loculi, divides the Anthozoa into — 
I. — POLYCYCLIA, with six primary tentacles and loculi, both increasing in 
number with age, forming two or more cycles. 
( 136 ) 
