. Elementary text-book of zoology. ANNULATA. 179 CHAPTER XVI. ANNULATA. POLYGORDIUS. ARENICOLA. HIRUDO. LUMBRICUS. I.—POLYGORDIUS. Fig. 105 —I'OLYGORDIUS Phylum- Annulata (p. 237). Neapolitanus. Sub-Phylum - Annelida (p. 238). Prostomial Tentacles. Class - Archiannelida (p. 239). Polygordius neapolitanus is a small delicate marine (1^2 inch) worm, of elon- gated body, found in the sand at moderate depths. It is of a pale pink hue. At the anterior end are a pair of small tentacles, the prostomial tentacles, covered with fine setse. They are parts of the prostomium, a lobular process lying anter
. Elementary text-book of zoology. ANNULATA. 179 CHAPTER XVI. ANNULATA. POLYGORDIUS. ARENICOLA. HIRUDO. LUMBRICUS. I.—POLYGORDIUS. Fig. 105 —I'OLYGORDIUS Phylum- Annulata (p. 237). Neapolitanus. Sub-Phylum - Annelida (p. 238). Prostomial Tentacles. Class - Archiannelida (p. 239). Polygordius neapolitanus is a small delicate marine (1^2 inch) worm, of elon- gated body, found in the sand at moderate depths. It is of a pale pink hue. At the anterior end are a pair of small tentacles, the prostomial tentacles, covered with fine setse. They are parts of the prostomium, a lobular process lying anterior and dorsal to the mouth. Immediately behind the mouth is the peristomium, a large and well-defined segment. The rest of the body is divided externally and internally into a series of segments. The terminal or anal segment is swollen and bears the anus. On its broadest part this segment bears a ring of papillae. The mouth leads into an oesophagus which continues as a simple intestine terminating in the anus. The ectoderm is a simple epithelium with unicellular glands ; it secretes a thin cuticle. Below it the mesoderm forms a well- developed system of longitudinal muscles. Inside them is the delicate coelomic epithelium, lining a spacious ccelom. This is divided by dorsal and ventral mesen- teries, in which are simple blood-vessels, and by transverse septa between each segment. Each segmental part of the coelom opens by simple paired tubes (or nephridid). to the exterior. The nervous system is still part of the ectoderm. It consists of a, brain in the prostomium,. Anus. Entire animal seen from dor- sal aspect X 5. (After Fkaipont.). 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 Masterman, Arthur Thomas. Edinburgh, E. & S. Livingstone
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