Volume 1

A student's text-book of zoology / by Adam Sedgwick.

  • Sedgwick, Adam, 1854-1913.
Date:
1898-1909
Catalogue details

Licence: In copyright

Credit: A student's text-book of zoology / by Adam Sedgwick. Source: Wellcome Collection.

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    Verril]; Leptopsammia Ed. and H.; Endopsammia Ed. and H.; Astroides Blainv. (Fig. 155); Lohopsammia'S.A. and H.; Rhodopsammia Semi)er; Rhizopsammia'Ven-. Fain. 2. Madreporidae. Colonial, arising by gemmation from the sides of the parent polyp : coenenchyma more or less abundant, spongy and reticulate, slightly or not distinct from the porous corallite-ivalls. Madrepora L.; Turbi- naria Okcn ; Astraeopora Blainv.; Montipora Q. and G.; ^nacropora Ridley. Fam. 3. Poritidae. Sclerenchyma reticulate and perforate. Septa never completely lamellary. Walls very jJorose. Corallites increasing by gemmation, and united directly or by intervening porous sclerenchyma. Foritcs Ed. and H.; Synaraea Verr.; Napopora Quelch ; Rhodaraca Ed. and H.; Alveopora Q. and G.; Diclioraca T. Woods. Sub-phylum II. CTENOPHORA.* Free-swimming, transgmrent ggelagic coelen-\ terata, icitli eight meridional rows of vihratile\ ' plates formed of fused cilia. They p>ossess e2. an oesogphageal tube—called the stomach— , j lined by ectoderm, and a gastrovascular i canal system. Nematocysts are cdmost ^' always absent. The fundamental form of the Ctenophora is a gelatinous, splierical, or ovoid body, Avhich swims in the sea by the activity of its ciliated plates. It has two poles—the oral pole marked by the mouth, and tlie ahoral jrole marked by the sense organ. The line connecting these two poles is the main axis, and in describing the structure of the body it is important to recognise two planes which pass through this axis at right angles to one another. The mouth leads into a tube called the stomach (sometimes called oesophagus or stoniodaeum, because it is lined by ectoderm), and the stomach opens into the central part of the gastro- vascular ajrparatus called the funnel (infun- dibulum). The stomach is furnished with two hepatic bands. Both stomach and funnel are flattened sacs, and both lie in the main axis—the funnel of course above the stomach—but with their long diameters Fig. 157. — HormipTiora (Cy- dippe) phimosa (after Clum). 0 mouth. * G. Chun, “Die Ctenophoren des Golfes von Neapel,” Fauna und Flora des Golfes von Neapd. 1880.