20 



POLYPIFERA. 



bodies, and forming, when dried, a sort of 

 coriaceous polypary. 



Zoanthus, Mamillifera, Corticifera. 



Fig. 24. 



Actinia sociata (Ellis'). Zoanthus (Cuvier). 

 {After Ellis.) 



Family 6. ACTINIADJE. Body soft and 

 fleshy, free, mouth furnished with several rows 

 of simple or branched tentacula. 



Actinia (fig. 45) Lucernaria, Moschata, Ac- 



tinecta, Discosoma, Actinodendron, Me- 



tridium, Thallasianthus, Actineria, Acti- 



noloba, Actinocereus, &c. 



Family 7. PENNATULID.E. Animals po- 



lypiform, with eight pinnated tentacles, more 



or less prominent, and regularly arranged 



upon a part only of a common polypary, 



which is free or adherent. Its form is deter- 



minate, and it is composed of a central axis, 



which is solid, and enveloped in a fleshy 



cortex, often of considerable thickness, and 



supported by calcareous aciculi. 



Pennatula (fig. 4-4), Renilla, Virgularia, 

 Scirpearia, Pavoniaria, Veretillum, Om- 

 bellularia. 



Sub-class 3. AULOZOA* (nobis), (Tubular 



Polypes.) 



Animals simple or compound, occupying 

 the interior of corneous or calcareous tubes, 

 which are either simple or ramified ; polypes 

 terminal or lodged in lateral cells ; repro- 

 duction multiform. 



Family 1. TUBULARID.E. Animals gene- 

 rally aggregated ; polypes terminal, not retrac- 

 tile ; reproduction by ova produced near the 

 bases of the tentacula, and unenclosed in any 

 cell ; polypary pergamentaceous or corneous, 

 simple, tortuous, or regularly ramified ; some- 

 times wanting; tentacula, numerous, solid. 



Tubularia (jig. 48.), Endendrum, Pennaria, 

 Syncoryna (fig. 47), Coryna, Hydractinia, 

 Stipula. 



Family 2. TUBIPORIDJE. Polypary com- 

 posed of calcareous tubes, arranged in succes- 

 sive stages like the pipes in an organ ; po- 

 lypes terminal, with eight pinnate arms. 



Tubipora (fig. 52). 



Family 3. SERTULARIDJE. Polypes hy- 

 driform, provided with simple tentacula, which 

 are never ciliated ; lodged in lateral cells of 

 various shapes and disposition, continued into 

 the interior of the tubular polypary, which is 

 ramified, horny, subarticulated, and fixed by 

 a root-like basis. 



Sertularia (fig. 55), Campanularia. 



f, a pipe or reed j &<, animal. 



Sub-class 4. BRYOZOA (Ehrenberg). 



Ciliobrachiata (Farre). 

 Animals polypiform, with the tentacula 

 around the mouth covered with vibratile 

 cilia, by the agency of which food is furnished 

 to the oral opening ; alimentary canal com- 

 plete, being furnished with an intestine and 

 distinct anal orifice ; body generally enclosed 

 in a corneous or calcareous cell ; with or 

 without an operculum. 



Eschara (fig. 57), Flustrae, Bowerbankia 

 (fig. 56), Pedicellina (fig. 65), Lagunculus 

 (/g.61), Cristatella Mucedo. 

 Polyps are invariably aquatic animals, some 

 inhabiting fresh water, but the great body are 

 marine, and most numerous in tropical seas. 

 In very high latitudes only Cellarians, Sertula- 

 rians, and Alcyons occur : and in the vicinity 

 of volcanic islands in the polar seas Coral- 

 lines and Gorgonians. These latter multiply 

 a little from 6 to 9 N. Lat., and as they ap- 

 proach the tropics attain their full powers of 

 growth and multiplication. Some frequent 

 the mouths of rivers where there is a conflux 

 of fresh and salt water ; some love atmo- 

 spheric influence, while others avoid it. The 

 marine ones frequently plant themselves on 

 rocks in different aspects, often regulated 

 by the climate. They rarely expose them- 

 selves to violent currents, or the direct shock 

 of the waves, being generally found in the 

 hollows of rocks and submarine caverns, and 

 in gulfs, where the water is less agitated. 



HYDROZOA. 



The Hydras are to be met with abun- 

 dantly in summer time in almost every pond 

 or ditch, and may easily be collected along 

 with the duck-weed or other aquatic plants 

 among which they reside. On filling a glass 

 jar with the water in which they reside, and 

 allowing it to stand for a few hours undis- 

 turbed, the little polypes will be found, some- 

 times in great numbers, adhering to the sides 

 of the vessel, in which position nothing is 

 easier than to watch their proceedings, and 

 with the assistance of a simple magnifier to 

 verify the descriptions which Tremble}' and 

 others have given of the extraordinary phe- 

 nomena they exhibit. 



The Hydra viridis, or short-armed polype, 

 which is the species most commonly met with 

 in this country, resembles, when expanded, a 

 little bit of green sewing-silk, about the sixth 

 part of an inch in length, attached by one ex- 

 tremity to the interior of the jar, or to any 

 other fixed body, and having the opposite end 

 slightly untwisted. 



When moderately magnified, the body of 

 the animal is found to be a little bag open at 

 one extremity, the opening, which is in fact 

 its mouth, being surrounded with seven deli- 

 cate filamentary tentacula ; while the other 

 end is provided with a little flattened disc 

 or sucker, by which it fixes itself to any 

 foreign body (fig. 25). Its substance seems 

 to be entirely composed of a gelatinous mate- 

 rial, in which are contained numerous green- 

 ish granular particles suspended in a glairy 



