CA R YOPH YLLIA CEA . 
ANGIADuE. 
THE WEYI^IOUTH CARPET-COEAL. 
Hoplangia Durotrix. 
(Sp. nov.) 
Plate X. Fig. 9.* 
Specific Character. Plates in four imperfect cycles. 
Phyllangia Americana. Gosse, Annals N. H. Ser, 3. ii. 349. 
GENERAL DESCRIPTION. 
Corallum. Compound, increasing laterally on all sides ; low, not rising 
above the height of the individual corallites ; iucrusting rocks. 
Corallites. Formed by budding from a permanent, thin, calcareous, 
carpet-like expansion, which spreads around the base of the parent, to 
which each is permanently united by the inferior portion of the wall. 
(In the specimen in my possession, four corallites of sub-equal size are 
grouped around a parent, which has been long dead, for the inner portions 
of its plates have been worn away.) They are cylindrical, deep, about 
twice as high as wide, slightly inclining outwards from the common 
centre. 
Wall, Invested by a thin porcelain-like coat of calcareous matter, 
which appears identical with the basal carpet. It terminates above with 
a perfectly defined, slightly everted edge, above which the wall is beau- 
tifully white and clean, while the epitheca is dirty white, and coated with 
a minute sponge. The epitheca shows traces of periodic growth, by a 
succession of such everted edges not totally obliterated ; and while in one 
corallite the edge is level with the summits of the plates, in another there 
is at least one-fourth of the total height above the epitheca. Hence 
I infer that the wall with the septa makes a periodic growth above the 
last level of the epitheca, while the latter remains dormant, and that then 
the epitheca is deposited at once around the new growth ; the wall and 
the epitheca thus growing alternately. The wall is covered with minute 
scattered granules, and these as well as the ribs can be discerned through 
the thin ejiitheca. 
Ribs. Thin, sharp, low, in some places discernible only at the very 
summit of the wall, in others nearly throughout : in the former case they 
appear again from the edge of the epitheca a little way downward. 
* Marked “ Ph yllangia A mericana ” in some copies. 
