674 Div. 4. RADIATA.— POLYPI. Class 4. 



TUBULARIA, 



Have the tubes of a horny substance, and simple, or branched ; and tne polypi come out at the 

 extremities only. Many of them are found in stagnant fresh water, on the surfaces of plants. 



Tubularia marina, have two ranges of tentacula, the exterior as rays, and the interior a tuft. T. indioita, 

 found in the European seas, have the tubes about two or three inches long, resembling bits of stone. Tibiana, 

 have the tubes in zigzag, with a small opening at each angle. Coniularia, have the tubes conical, and the polypi 

 have eight toothed tentacula. Anguinaria, have small cylindrical tubes, adhering to a creeping stem, with an 

 opening near the e.xtremity for the polypus. Cainpanularia, have the terminal habitations of the polype bell- 

 shaped. Some have the branches of the bell smaller, and others have climbing stems. 



Sertularia, — 

 Have a horny stem, simple or branched, with the cells for the polypi on the sides. The common 

 gelatinous stem forms the axis of the horny one. They propagate by buds, which are produced in 

 larger cells. The dispositions of the cells have caused various subdivisions. 



Aglaophenia, have the cells on one side of the branches. Amatia, have the cells partially united, and in some 

 cases forming a sort of spire. Antennularia, have the cells in horizontal whirls ; a.nd Heriularia proper, have 

 them alternate or opposite, on both sides of the stem. 



THE SECOND FAMILY OF THE CORALLIFERA,— 

 The Cellularia, — 



Have each polype adhering to a horny or calcareous cell with thin walls, and no apparent connection 

 with each other, except by a very thin epidermis, or by pores in the walls of the cells. The polypi in 

 general resemble Hydra. 



Cellularia, have the cells arranged in the form of branched twigs, but no communicating axis, and the substance 

 of their stems is more calcareous. There are several subdivisions. 



Crista, with cells in two ranks, generally alternate, ajid opening on the same side. Acamarchus, with a vesicle 

 at each opening. Loricula, with two cells opposite, placed back to back. Eucratea, with one oblique cell on each 

 articulation. Salecorniaria, with the joints of the stem hollow, and their surfaces studded with cells in quincunx. 



Ftustra. — This genus consists of many cells, united in clusters like a honeycomb, sometimes covering various 

 bodies, and sometimes forming leaves or stems. Some species have cells on one side the leaves only. 



Cellepora, have numerous small calcareous cells, crowded upon each other, and each pierced by a small open- 

 ing. Tubtilipora, are masses of little tubes with wide openings. 



There are bodies in the sea, which resemble the Coralliferi, or Polypi having stems or polypidoms, 

 in which no polypi have yet been discovered. Pallas, and other naturalists of name, have considered 

 them as plants ; but others regard them as polypidoms, in which case they belong to this order. They 

 form one great genus, with many subdivisions. This genus is 



CoRALLiNA (the Corallines), — 

 Which have articulated stems, supported on a kind of roots and branching again and again, but having 

 no pores in their substance, or visible polypi. 



Corallina projier, have the calcareous joints of uniform appearance, and there is no sign of epidermis or bark. 

 The bottom of the sea on certain coasts is covered with these like a thicket of bushes, having the joints oboval, 

 and the sprays arrayed like pinnate leaves. The colour is white, or reddish, or greenish. It was once used in 

 medicine, though only on account of the salts of lime which it contains. Amphinva, has the joints elongated. 

 Jania, have them slender, and with less calcareous matter. Ciimnpolia, has the cal'-areous joints separated from 

 lach other by jjorlions of horny matter, and pores more distinctly marked than most of the others. Pcnidlla, 

 have the interior of the stem composed of a tissue of horny threads, with an external calcareous crest investing 

 the whole. The stem terminates in a bundle of tirticuliited branches, resembling those of the other Corallines. 

 JJali/metla, have the steins and branches composed of joints externally, like the others ; but internally they have 

 a corneous tissue, from which the cutaneous matter is easily separable by acids. Flahellmius, have no distinct 

 joints; but consist of large leaf-like expansions, which have their stems of the same consistency as those of 

 Halymeda. Galaxura, have the stems hollow, mid branching into two. Lingora, resemble the last, but have no 

 articulations in the stems. Anadiomena (Corsican Moss), is articulated and branched, and consists of a horny 

 substance, with a gelatinous covering. It is much used for expelling worms. Acetabulum, is in form one of the 

 most singular of the Corallines. It consists of a slender stem, supporting a round thin plate like a parasol, which 

 lias a round smooth disc surrounding the central pores, the outer portion mariced with striae, and the margin 

 crenuliited. No polypi have been discovered in their pores ; but the rays of the striated disc are hollow, and con- 

 tain greenish granules, which led Cavalini to conclude that it is a vegetable. Poh/phi/sa, have a hollow stem, 

 with a bundle of small closed vesicles on the summit. This has also been considered a vegetable. 



