[ JOO 1 
often be picked up on the shore. Some of the best known 
genera belon^^ing to this order are St^rlnlarin, Plumnlana anrl 
Antemiularia. Others forni a skeleton of lime, like Millepnra 
and Stylaster and thus resemble true Corals. Miifepora grows 
in solid masses, whilst the various species of StyLtsier are deli- 
cately branched and exquisitely coloured, white, pink and 
salmon. 
JELLY-FISHES (Scyphozoa), 
This class includes most of the Jelly-Fishes or Medusae. 
Whilst Hydra, the type of the former class, is tubular, the 
Jelly-Fishes are bell or umbrella-shaped. They also have an 
ectoderm and an endoderm, but between the two and secreted 
by them is an additional layer, the mesogloea, of gelatinous 
consistency, which is often extremely thick and constitutes the 
chief mass of the body. The roof of the bell corresponds to the 
foot of the Hydra, whilst the mouth of the Medusa lies on the 
under side of the body, between the tentacles. Medusae occur 
in all seas and are generally seen near the surface, where 
through the pulsating movement of their wonderfully shaped 
and wonderfully coloured, semi-transparent bodies they offer 
a most interesting and beautiful spectacle. They vary greatly 
in size. Some are as much as three or four feet in diameter. 
CORALS and SEA ANEMONES 
(Anfhozoa or Actimmoa), 
The Antho/.oa differ from the two former classes in 
having a special tube which leads from the mouth tt» the 
coelenteron, and in this latter cavity being divided by a number 
of vertical partitions, called mesenteries or septa, into as many 
compartments. A section across the body of a Sea Anemone or 
Coral would therefore appear like a wheel with its spokes. 
There are either 4, 6 or 8 of those mesenteries and compart- 
ments, which allows the class to be divided into Tetracoroflhi, 
Hexac&raUiu, and Octo€(mdlt\f. The Tetracondlui are known in 
the fossil condition only. 
The Octocorallia or Atcyo/kirui have eight tentacles and 
eight mesenteries. Akymtium digit urn or Dead Man*s Finger 
is common on rocks of the English coast. It forms lobed or 
finger-like masses of white or yellowish colour, the polyps being 
held together by a fleshy substance (mesogloea), imbedded in 
which are spicules of lime. Allied species of .4^nw//H/w occur 
