398 



ZOOPIIYTA.- 



-RADIATA.- 



-Antiiozoa. 



I;iiown by the name of the Girdle of Venus [Ctstum 

 Veneris) a native of tlie Mediterranean. 



Order III.— CIRRHIGRADA. 



Tliis order of Acaleplis contains a number of animals 

 tlie body of which is almost membranous, oval, or 

 circular iu shape, and supported by an internal sub- 

 cartilaginous part. Their organs of locomotion consist 

 of numerous e.xtensile, tentacular cirrhi, pendent from 

 the whole of the under surface ; and it is by the action 

 of these organs that their motion through the water is 

 effected. The order is well represented by the Vdclkv 

 and Porpitce. 



Genus Velella (the Sallee-man). — This genus, 

 forming the type of the family Velellidce, is represented 

 iu riate 1, fig. 8, by the species V. cyanea. 



Genus Poui'ita. — This genus, forming the type of 

 another family, is represented by Porpita ijitjantea in 

 riate 1, fig. 7. 



Order-IV.— niYSOGRADA. 

 TliC animals belonging to this order are characterized 



by their possessing one or more vessels filled with air, 

 by means of which they keep themselves s\ispended 

 in the water; and by their being furnished with more 

 or less numerous cirrhiform tentacula attached to these 

 air vessels. The species are numerous, and are dis- 

 tributed throughout several families. 



The family PhijsophoridcB contain several genera 

 composed of animals found floating on the surface of 

 the sea, and is represented in Plate 2, fig. 2, by 

 PlojsaUa pelmjica (or megalista), the common "Portu- 

 guese man of war," as it is called ; and in Plate 1, fig. 

 5, by Physophora disticha* 



The family Diphydce consists of gelatinous trans- 

 parent little creatures, which appear, when closely 

 examined, to consist of two crystalline-looking pieces 

 like bits of glass. These two portions are always found 

 the one included within the cavity of the other, but 

 capable of being separated without injury to each other. 

 The family is represented in Plate 1, fig. 4, by the 

 beautifully delicate Diphyes Boryior Campanullfira, an 

 exotic species, but which is sometimes thrown up on 

 our own coasts, particularly the flat sandy beaches of 

 Norfolk and Suftblk. 



Class III.— ZOOPHYTA* or POLYPI (Zoophytes or Polyps). 



This class of radiated animals is thus characterized 

 by Milne Kilwards: — Animals organized for a sedentary 

 mode of life, having no locomotive organs, and being 

 provided with a circle of retractile tentacula round the 

 mouth, and a central gastric cavity not communicating 

 with a vent, and containing the reproductive organs 

 when they exist ; in general fissiparous or multiplying 

 by buds as well as by ovules. They received the name 

 Zoophytes (animal plants) because the animals are often 

 crowded together in societies or families in such a 

 manner as to assume the form of trees — a form assumed 

 so as to allow each of the individuals of which the 

 society is composed to procure a fair and equal share 

 of nourishment from the water which surrounds them 

 and on which they live, as the leaves of trees extract 



nourishment from the air in which the plant grows. 

 The union which they form with each other is some- 

 times so intimate, that one individual cannot be injured 

 without its becoming felt by the whole society. The 

 permanent f;ibric formed by these animals is called 

 Pulypidom (the house of the Polyps). The Zoophytes, 

 taken as a class by themselves, have been divided into 

 two sub-classes or divisions, according as the animals 

 assume the radiated or the molluscan type. These are 

 termed the Antliozoa, or Radiated zoophytes; and the 

 Dryo'Ofi, or Molluscan zoophytes, which are now con- 

 sidered by many naturalists to form a class of Molhisca, 

 following and nearly related to the Tiinicata. Many 

 of the more transparent Zoophytes are highly hiQiinous. 

 See page 381, Mulluscci. 



Sub-class I.— ANTIIOZOA.t 



Tiioucii we retain here this sub-class of Anthozoa, or 

 " animal Sowers," as part of the class Zoophyta, we are 

 aware that from late observations made as to their 

 structure, the animals of the Anthozoa appear to be 

 closely related to the Medvsce, and form indeed, accord- 

 ing to these observations, a sub-order oi the Pulmogi-ada 

 or Discoplioro'. 



The animals forming the Antliozoa may be thus 

 characterized : — Body tending to globular, contractile 

 in every part, sjmmetrical; mouth and vent one; 

 gommiparous and oviparous ; mouth surrounded wilh a 

 circle of retractile non-ciliated tentacles. They are 



• From zoon {K'im) an animal, and phyton {^um) a plant. 

 t From anthos {ctvQoir) a flower, and zoon {ii^ov) an animal. 



divided into three orders, which contain numerous 

 interesting species — 1. Hydroida; IL Asttroida ; III. 

 Heliantlwida. 



Order I.— ANTHOZOA HYDROIDA {ffydroid 

 Polyps). 



In this order of Zoophytes, the permanent fabric, the 

 " House of the Polyps," the Polypidom, is horny, fistular, 

 external, and plant-like. The Polyps themselves are 

 generally compound, and have the body for the most 

 part of a somewhat globular figure, and of a nearly 

 homogeneous composition, consisting of an aggregation 



* Tlie figure is reversed or turned upside down in the Plate. 



