1281 



ZOANTHARIA. 



ZOARCES. 



1231 



creatures included in this order, and the important part they hav<_ 

 played in the formation of the crust of the earth, have rendered them 

 favourite objects of study with both zoologists and geologists, whils 

 the size to which they attain, greatly exceeding that of most other 

 zoophytes, has enabled the anatomist to investigate their interna 

 organisation in a very satisfactory manner. In the present state of our 

 knowledge of their structure their essential characters may be summee 

 up as follows : Polypes separate or conjoined, free or attached, more 

 or less cylindrical or expanded, mostly regular and circular, the parts 

 arranged around a centre ; mouth contractile at one extremity of the 

 axis, opening into a large stomach capable of protrusion, terminating 

 in a 'cul de sac," and furnished laterally with longitudinal folds 

 Between the walls of the stomach and the epidermis are numerous 

 muscular lamella;, and in the interspaces are the ovaries and (ccccal ? 

 lilarnental appendages. Tue mouth is surrounded by a disc, usually 

 tentaculiferous (in some species the tentacula are obsolete). Teutacula 

 simple or pinnate, hollow, their internal walls clothed with vibratile 

 cilia, which also are found on the ovaries. 



The state of the nervous system is still doubtful. Wagner has 

 lately asserted the bi-sexuality of these zoophytes. 



The posterior extremity of the body is in some species elongatec 

 and acute, in others it forms a suctorial disc ; in a great number it 

 secretes in its tissues calcareous matter, which is disposed in regulai 

 form, and constitutes the coral or polypidom, and in the group o: 

 Coriaceous Zoantharia expands into a leathery fixed crust, which 

 forms a common base for several individuals. 



The Zoantharia may be grouped under four very natural families, 

 namely : 



I. Lucernariada, the animals included in which are soft and simple, 

 fixed by a small base or free, and having the tentacula in groups at 

 regular distances on the margin of a campanulate disc, in the centre 

 of which is the mouth. 



II. Actiniadce: animals all soft and simple, fixed or free; when fixed, 

 adhering by a broad base ; the tentacula in most species developed 

 and surrounding the margin of the oral disc. 



III. Zoanthida : animals coriaceous, simple or compound, fixed; 

 tentacula marginal, surrounding the mouth. 



IV. Madreporidce (including the 'Madrcphylliwa of De Blainville) : 

 animals forming a solid calcareous polypidom ; in other respects they 

 resemble the Actiniadie. 



Family I. Liicemariadce. 



The animals of tbia family belong to a single genus, that of Lucer- 

 tiaria, established by 0. F. Miiller. They are campanulate, and fixed 

 to sea-weeds by a narrow disc or stalk, from which they expand into 

 a broad octagonal disc, in the centre of which is a quadrangular 

 mouth, and at each angle a bundle of tentacula. In the intermediate 

 spaces are little coloured lobes, which have been regarded by some 

 naturalists as organs of vision ; surrounding the mouth festoons of 

 ovaries are seen. All the species known ura inhabitants of the British 

 and Norwegian seas. The largest measure about an inch in height. 

 They are of various colours, but usually pink. They swim with 

 rapidity, by alternately dilating and contracting their bodies, but 

 unually adhere to sea weeds, where they feed on small Crustacea, 

 which Lamoureux asserts they perceive in the water and endeavour to 

 ' ize. Their habits have been observed by Otho Fabricius, Montagu, 

 Flemming, and Dr. Johnston, whose work on British zoophytes contains 

 a good account of the several species. 



Although Cuvier, Blainville, Ehrenberg, and Johnston have all 

 placed the Lucernaria among the fleshy polypes, some writers dissent 

 from such an arrangement M. Dujardin remarks, "Wo ought to 

 draw a great distinction between the papilliform tubercles of the arms 

 of Lucernaria, and the extensible tentaculaof Actinia. Perhaps when 

 the structure and quaternary arrangement of their ovaries, approach- 

 ing that of the Medutce, are considered, they ought to be approximated 

 to the latter type." 



L auricula is the best known species. 



Lucrrnanu auricula. 



Family II. Actiniadce. [ACTINIADJE.] 



Family III. Zoanthidce. 

 It comprises the following genera : 

 Xoanthui, Cuvier. The body is elongated, conic, and pedunculated, 



MAT. BUT. D1V. VOL. IV. 



springing from a base common to several individuals. The mouth is 

 linear and transverse, in the centre of a disc bordered by short slender 

 tentacula. 



Z, Couchii of Johnston is the only European representative of this 

 family. It is found on the British coasts. 



Mammilifera, Lesueur (Polyt/toe, Lamoureux). The body is coria- 

 ceous, short, and niammiliform ; slightly enlarged at its buccal 

 extremity, and provided with several rows of marginal tentacula. 

 It is sub-pedunculated at the base, and springs from a common 

 expansion. 



M. awrimlata is a native of the West India Islands. 



1, Zoanthus Svlanderi ; 2, Corticifcra glarcola ; 3, Slammili/era awictituta. 



Corticifera, Lesueur. Body short, cylindrical, having a longitudinal 

 mouth surrounded by petaliform tentacula at one extremity, and 

 merged at the other into a common mass with numerous similar indi- 

 viduals, so that a solid poliferous crust is formed. Thus there is a 

 transition through this genus from the soft Actinice to the Corals. 



C. glareola is found in Guadaloupe. 



The best account of the Zoanthidce, with excellent figures, will be 

 found in the papers of Lesueur, in the first volume of the ' Trans- 

 actions of the Philadelphia Academy." 



Family IV. Madreporidce. 



The animals which form the harder and larger corals closely 

 resemble the Actinia. Generally, as far as they have been examined, 

 there is but little variety among them; but judging from the differ- 

 ences presented by one or two types, it is probable that future 

 researches will show a greater diversity of form in this family than is 

 at present admitted. Thus, though the usual form of the coral animal 

 is that of a cylinder terminated by a disc surrounded by simple tenta- 

 cula, in Fungia, we have the tentacula irregularly scattered over a 

 broad expansion; and in Dcsmophyllum they are reduced to the 

 appearance of irregular folds. [PoLYra'EiiA ; MADREPIIYLLICEA; 

 MADREPOMIA; 



Animal of Cladvcora faspitosa. (From an original drawing.) 



ZOARCES, a genus of Fishes belonging to the family Gobiadie. 

 t has an elongated body, covered with a mucous secretion ; the head 



4 N 



