. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). Wl^^SSSm TYPE M0LLU8CA. 315 general th their ut; and )tc., are ^neumo- isomata, la beiug of the 3 shell itrical, s?,§ the ed by linous iiioso- eniity bear itacle- rhaps \i modifications of portions of the foot, being innervated from the pedal ganglia. In these forms also fringed or simple pro- cesses of the posterior portion of the body occur which serve as respiratory organs, though they are not homologous with the true branchia which in Pneumoderma coexist with them.
. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). Wl^^SSSm TYPE M0LLU8CA. 315 general th their ut; and )tc., are ^neumo- isomata, la beiug of the 3 shell itrical, s?,§ the ed by linous iiioso- eniity bear itacle- rhaps \i modifications of portions of the foot, being innervated from the pedal ganglia. In these forms also fringed or simple pro- cesses of the posterior portion of the body occur which serve as respiratory organs, though they are not homologous with the true branchia which in Pneumoderma coexist with them. Suborder Nudihraiichia. In the Nudibranchs the visceral hump has undergone elongation parallel with the long axis of the foot, from which it is not distinctly marked off, and an apparent bilateral sym- metry is manifested by the body. This condition, however, is evidently entirely secondary, as is shown by the structure of the heart and nephridium, in which the usual asymmetry' is well marked. There is no shell, mantle, or cteuidia. Adaptive branchiae are, however, frequently developed, as in Pleurophyl- Udia, where they form a series of folds which lie in a groove at the side of the body and recall somewhat the arrange- ment in the Chitonidse, or in Boris, where they surround the anus, which has a dorsal position, and form a circle of pin- nate processes. In the pelagic Phyllirhoe and in the creeping Limapontia, however, there is no trace of respiratory organs. Many forms (Fig. 141), such as ^oJis, FacelUna, and their allies, bear upon the <lorsal surface of the body numbers of fluger-like processes usually arranged in bunches, and frequently brightly colored. These cerata frequently enclose branches ii'om the intestine which correspond to the digestive gland of other forms, and p^^ ^^^ bear at their extremities a sac in which are developed nematocysts. These organs are usually richly provided with blood- vessels, and are probably respiratory in function, though the pres
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1894
