Organs employed in the Classification of the Mollusca. 393 



of Auricula agrees with that of marine Mollusca, according to 

 Dr. C. Semper, although the most allied forms {Limncea) are not 

 subject to this kind of metamorphosis. 



All the terrestrial forms leave the egg in a perfect state. The 

 Cephalopoda may be considered Gasteropoda stopped in the 

 larval stage, reminding one of Macgillivrayia. The number of 

 the eggs may also be of some importance for the determination 

 of superiority and inferiority, as nature seems to compensate 

 want of intelligence, or power to provide for the offspring, by 

 great fertility : thus plants are more fertile than animals ; the 

 Helicea produce but few eggs compared with the Acephala. 

 Since the time of Cuvier nearly all naturalists have considered 

 the Cephalopoda the highest type of Mollusca, chiefly on account 

 of a presumed affinity with the Fishes, their great size, great 

 muscular power, as well as the apparent superiority of the 

 nervous system and organs of circulation. Naturalists are not 

 yet agreed which families may be considered the highest in 

 each class, except in the Mammalia. Among the Birds, the 

 Parrots are considered the highest by the best authors; the 

 Serpents may perhaps be the highest Reptiles, although such 

 an authority as Prof. Agassiz considers the Chelonians the 

 highest, on account of the completeness of the ossification. 

 According to this principle, the Edentata would be the highest 

 Mammalia ! The largest and strongest Arthropods, the Lob- 

 sters, have a similar claim to be considered the highest of that 

 subkingdom. Marine animals are always larger than their kin- 

 dred on the land, but not the most perfect, as Prof. Agassiz 

 has proved. 



The systematic place of the Cephalopoda may depend on the 

 structure of the heart and the explanation of the hectocotylized 

 arm as a male organ. If the brauchiocardiac veins of Cephalo- 

 poda may be considered auricles, as stated by Milne-Edwai'ds, 

 KolUker, Huxley*, and Gegenbaurf, the place of the Cephalo- 

 poda must be between Dentalium and Acephala J — a place not 

 more strange than that of the CacilicB standing before the Pla- 

 giostomes, or the Linguatula before the Decapod Crustacea. 



The hectocotylized arm of the male indicates a kind of copu- 

 lation between two individuals, giving the Cephalopoda claim to 

 a higher place than the Acephala; but it must be remembered 

 that the manner of copulation of the Pseudophallia is entirely 

 unknown at present. 



If the cardiac auricles only prove to be tumefactions of the 



* On Morphology, &c. p. 57 — " the presutned highest Mollusca." 

 f Vergleichende Anatomic, p. 375. 



X Solen swims, according to Prof, Deshayes, like the Cephalopoda, by 

 driving water out of the respiratory cavity. 



