164 
PHYLUM C@LENTERA. 
ANTHOZOA OR ACTINOZOA 
ZOANTHARIA, HEXACORALLA, ¢.g. 
SEA-ANEMONE. 
ALcYoNARIA, OCTOCORALLA, 6.2% 
Drap-MEn’s-FINGERS. 
Many are simple, many colonial. 
The polyps of a colony may give rise 
to others directly by fission or 
budding. 
Tentacles usually simple, usually some 
multiple of six, often dissimilar. 
Mesenteries usually some multiple of 
six, complete and incomplete. 
Retractor muscles never as in Alcyo- 
naria. 
Two gullet grooves or siphonoglyphes, 
or only one. 
No dimorphism. 
Calcareous skeleton, if present, is derived 
from the basal ectoderm. 
Examples. 
Sea-anemones—eg. Tealia and 
Actinia. 
Madrepore corals, many of them reef- 
building. 
Antipatharians. An aberrant Anti- 
patharian, Dendrobrachia fallax, 
has e7ght feathered tentacles, 
All colonial, except a small family in- 
cluding Monoxenia and Haimea. 
The polyps of a colony give rise to 
others not directly, but through 
stolons or solenia. 
Tentacles eight, feathered, uniform. 
Mesenteries eight, complete. 
Retractor muscles always on one (ven- 
tral) side of each mesentery (see 
Fig. 81). 
One (ventral) gullet groove (siphono- 
glyplfe or sulcus), or none. 
Frequent dimorphism among members 
of a colony. 
There are usually calcareous spicules (of 
ectodermic origin) in the mesoglcea. 
Examples. 
Alcyonium (Dead-men’s-fingers), with 
diffuse spicules of lime. 
Tubipora (Organ- pipe coral), with 
spicules fused into tubes and trans- 
verse platforms. 
Corallium rubrum (Red coral), with an 
axis of fused spicules. 
Pennatula (Sea-pen), a free phosphor- 
escent colony, witha ‘‘horny” axis, 
possibly endodermic. 
ZOANTHARIA 
The Zoantharia include many orders, ¢.g. the primi- 
tive Cerianthidea (Cerianthus, etc.) and Edwardsiidea 
(Zdwardsia), the Actiniidea (including the typical sea- 
anemones and the Madreporaria), and the divergent Anti- 
pathidea. 
Making of a typical coral.—Although the term “ coral” 
is applied to many different Ccelenterate types with 
substantial calcareous skeletons, e.g. to Millepores which 
are Hydrozoa, and to “blue corals” and “red corals” 
which are Alcyonarians, the corals par excellence are the 
Madreporarians. They form the coral rock and “coral 
islands” found in many parts of the globe, but rarely north 
or south of a belt extending 30° on each side of the 
equator, and rarely below the 4o-fathom line. 
