Elements of conchology Prepared Elements of conchology / Prepared for the use of schools and colleges elementsofconcho00rusc Year: 1844 26 NERVES OF CEPHALOPODS. also terminate in ganglia, from which arise a great many filaments. In the tetra- branchial cephalopods, the oesophageal collar is simply protected by the cephalic car- tilage; but in the dibranchial cephalopods, in which the nervous system acquires its highest degree of develop- ment, this medullary mass is lodged in a special cavity, hollowed in the cartilage through which the oesopha- gus passes. 13. The cephalopods are never her
Elements of conchology Prepared Elements of conchology / Prepared for the use of schools and colleges elementsofconcho00rusc Year: 1844 26 NERVES OF CEPHALOPODS. also terminate in ganglia, from which arise a great many filaments. In the tetra- branchial cephalopods, the oesophageal collar is simply protected by the cephalic car- tilage; but in the dibranchial cephalopods, in which the nervous system acquires its highest degree of develop- ment, this medullary mass is lodged in a special cavity, hollowed in the cartilage through which the oesopha- gus passes. 13. The cephalopods are never hermaphrodite, as are most others of the mollusca. The ovary is always simple and lodged at the bottom of a sac formed by the body of the animal; sometimes there is but a single .oviduct; at others, we find two, which open at the base of the fun- nel; finally, all these ani- mals are oviparous. 14. All these mollusks are marine: they are very voracious, and feed chiefly on Crustacea and fishes, which they seize by the aid of their supple and vigorous arms, and easily devour by means of their sharp mandibles. Their flesh is eaten. 15. This class is divided into two families. Fig. 11. NERVOUS SYSTKM OF THE NAUTILUS. Explavation of Fig. 11.—Nervous system of the Nautilus :—c. the brain; —0. the optic nerves ;—g. the sub-cesophag-eal or thoracic g-anglia,;—t. the tentacular g'angHa ;—p. nerves of the tentacula ;—e. the nerves of the funnel; —a. a gangUon from which arise other teiTtacular nerves (/>) ;—d. a second, and similar ganglion, also giving rise to tentacular nerves (/);—in. nerves of the mantle, «fec.—v. the great visceral nerves, each of which gives rise to a ganglion (gv), from which the principal nerves of the viscera take their origin. 13. Do cephalopods lay eggs? 14. Where are cephalopods found ? Upon what do they feed ? 15. How is the class of cepkalopods divided ?
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