. A text-book of invertebrate morphology. Invertebrates. 122 INVERTEBRATE MORPHOLOGY. of the cavity is formed of high ciliated cells probably nervous in function, and above them is a mass of otoliths supported on four incurved rods of fused cilia, one of which forms the termination of each of the four meridional grooves. In addition to this sense-organ, which is to be regarded as of the same function as the otocysts of the medusae, there. Fig. 67.—Pleurobrachia seen pok the Abohai. Pole (after Agassiz). eg = ciliated groove. p = polar area. oi = otooyst. re = radial caual. i = tentacle. lies a
. A text-book of invertebrate morphology. Invertebrates. 122 INVERTEBRATE MORPHOLOGY. of the cavity is formed of high ciliated cells probably nervous in function, and above them is a mass of otoliths supported on four incurved rods of fused cilia, one of which forms the termination of each of the four meridional grooves. In addition to this sense-organ, which is to be regarded as of the same function as the otocysts of the medusae, there. Fig. 67.—Pleurobrachia seen pok the Abohai. Pole (after Agassiz). eg = ciliated groove. p = polar area. oi = otooyst. re = radial caual. i = tentacle. lies at each end of the sagittal axis of the sensory dome a so- called pole-area (Fig. 67, p), the cells of which are furnished with small plates of fused cilia, each area being surrounded by a thickened ciliated rim. These structures are from their form and situation supposed to be sensory, and an olfactory function has been attributed to them. The tentacles (Fig. 67, t), of which there are two, situated at the extremities of the transverse axis, are present in all forms except the Beroids. Each tentacle lies in a deep depression termed the tentacle-sJieath and consists of a princi- pal axis which gives rise to a large number of secondary tentacles arranged upon one side only. Both the primary axis and the secondary tentacles are solid, being composed mainly of muscle-cells and containing no prolongation of the tentacular vessel. In Mnemiopsis and its allies and in Cestum. 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 McMurrich, J. Playfair (James Playfair), 1859-1939. New York, H. Holt and Company
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