. The Cambridge natural history. Zoology. 4IO COELENTERATA ANTHOZOA The stomodaeum exhibits a single long deep siphonoglyph, which is probably dorsal in position. There are two tentacles to each inter-mesenteric space, one being marginal and the other cireumoral. The gonads are borne upon alternate mesenteries, and both ova and spermatozoa are produced by the same individual. The ectoderm of Cerianthus is remarkable for the immense number of nematocysts and gland cells. The latter secrete a. M^^m Fig. 179.—Cerianthus membranaceus. Colour pink, with tentacles annulated pink and brown. About 35
. The Cambridge natural history. Zoology. 4IO COELENTERATA ANTHOZOA The stomodaeum exhibits a single long deep siphonoglyph, which is probably dorsal in position. There are two tentacles to each inter-mesenteric space, one being marginal and the other cireumoral. The gonads are borne upon alternate mesenteries, and both ova and spermatozoa are produced by the same individual. The ectoderm of Cerianthus is remarkable for the immense number of nematocysts and gland cells. The latter secrete a. M^^m Fig. 179.—Cerianthus membranaceus. Colour pink, with tentacles annulated pink and brown. About 35 cm. in length. (After Andres.) quantity of mucus which binds the threads of the discharged nematocysts into a sticky feltwork and this secures particles of sand and mud, the whole forming a long tube in which the animal freely moves. This tube is often of considerable thickness. It is tough and resistant, smooth inside but ragged and muddy outside. It is often many times the length of the animal's body. The embryo of Cerianthus is set free before the completion of segmentation, and it gives rise to a floating pelagic larva known as Arachnactis. It has a variable number of tentacles and mesenteries according to its age, but when it reaches a size of. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Harmer, S. F. (Sidney Frederic), Sir, 1862- ed; Shipley, A. E. (Arthur Everett), Sir, 1861-1927. ed. [London, Macmillan and Co. , Limited; New York, The Macmillan Company
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
