SIMILITUDE TO CORALS. 367 
wound, and the Hschara flabellaris, a very curious polyzoon of the same genus. The latter 
is remarkable for the hood or helmet-like ovicells. About eleven species of this genus 
are known. 
In the illustration on the opposite page is shown one of the most curious of the polyzoa, 
named, from the external resemblance which its apertures present to the meshes of a net, the 
etepora, or Net-pored animal. The polyzoary of this species is hard, chalky, is only pierced 
on one surface, and has so much the appearance of the true stony corals, that it might easily 
be mistaken for one of these objects. It is a European species, and the specimen represented 
of the natural size. 
The next interesting family of polyzoa is called Selenariade, because they are round as 
the full moon, or Norval’s famous shield. In the circular form of the margin they all agree, 
but differ considerably in their curvatures, some being with one side plane and the other con- 
vex, while others are convex-concave, like a watch-glass, or, to speak more accurately, like the 
lens technically called a meniscus. They are all remarkable for their very large vibracula. 
One of these creatures is called Cupularia lowei on account of its resemblance to a dome. 
A good example of a very shield-like genus of this family is the Selenavia maculata. The 
reader will not fail to remark its exact resemblance to the target-shield used by many nations, 
ancient and modern. It may be here mentioned that in this last-mentioned family the vibracula 
are thought by some naturalists to act as locomotive organs. 
Our space is so rapidly drawing to a close, that it will be hardly possible to give much 
more than a brief account of a few more interesting examples. 
In the group of polyzoa Iam going to describe, there is a great external similarity between 
their forms and those of the true stony corals so familiar to us. It will, moreover, be found, 
that in many details of their structure, there is a decided analogy between them and the true 
zoophytes which will be described in the latter part of the work. 
In the Crisia eburna the arrangement of the cells is simple and elegant, and the various 
branches are connected with each other by means of certain horny joints. The use of these 
joints is, in all probability, to enable the polyzoary to resist the action of the waves, and so to 
avoid the fractures which would probably result if the joints were as stiff and inflexible as the 
cells. A similar provision will be seen in the Gorgonia, a zoophyte which will be described 
on a future page. 
A remarkably constructed species, the Zdmonea atlantica, looks something like a many- 
legged spider, with its branches protruding from a rounded centre which represents the body 
of that animal. 
A polyzoon remarkable for the profusion and great comparative length of the cells, is 
termed Pustulopora delicatula, the generic name being on account of the minute dots with 
which the surface of the cells and polyzoary is studded, and the specific title in reference to 
the delicate structure and soft brown hue with which it is colored. 
A stoutly-built polyzoon named Hornera, is notable for its resemblance to several corals. 
Iy the accompanying illustration, the resemblance to the corals, the madrepores, and even 
the stony habitations of certain marine worms, is very close and striking. 
Fig. A represents a polyzoon fancifully entitled Alecto, in honor of one of the Furies of 
that name. It is seen of its natural size as it appears while spreading itself over the inner 
surface of a shell. At Fig. B, a portion of the same species is shown as it appears when 
magnified, and is given to exhibit not only the method in which the cells are sunk into the 
polyzoary, but the mode in which the branches are developed from each other. 
At Fig. C is delineated a portion of the appropriately named Tubulipora serpens, a being 
which has the cells even more elongated than in the Pustwlopora which has been lately 
described. The singular resemblance between the lengthened cells of this species and the 
hard shelly tubes of the well-known Serpula, so familiar on account of its scarlet and white 
plumes and marvellously engraved stopper, must be evident to every one who has seen the 
little creature. or even noticed its empty habitation. 
