530 HISTORY OF SYSTEMS. 



the Cephalopods, to wliom they were inferior in organiza- 

 tion, because, forsooth, M. Lamarck chose to believe that 

 Nature, in her successive production of the different classes 

 of animals, could not pass from a lower to a higher one, 

 except by first falling back on her steps, — by, as it were, 

 degrading herself to animate an order of weak and anomalous 

 beings wherein she, for a time, nursed her energies to be 

 enabled to take the forward leap in structural organism which 

 fate was ever impelling her to make. You may find the doc- 

 trine indicated by the greatest of Scottish bards, when he 

 sung of Nature trying her apprentice hand in a coarser clay 

 before she attempted her master- piece of creation ; and you 

 may indulge your national partiality, if you choose, in trac- 

 ing back the theory of self-development to this tuneful 

 source. The doctrine of the development of the flower from 

 the leaf draws its origin from a not more illustrious poet. 



The Pteropods were embraced in a single family, into 

 which the new genera established by Peron and Lesueur 

 were introduced, with the exception of the Carinaria and 

 Pterotrachea, which were considered to be heteropod ; and 

 of the Callianires, which were remanded back to their sta- 

 tion in the radiated svibkingdom. The old order of Gaster- 

 opods was dismembered, and greatly curtailed in its demesne, 

 by the elevation of the Trachelipods to a coequal rank ; but 

 you will at once perceive the unnaturalness of this proceed- 

 ing, when I tell you that the slug is a Gasteropod, and the 

 snail a Trachelipod, — genera which certainly are at least 

 ordinally connected. The two orders do, in fact, pass into 

 each other by a series of transition species, so that it is fre- 

 quently a question to which order some of them ought to be 

 related ; and hence it follows, that the more or less separa- 

 tion of the foot from the ventral aspect of the body does not 

 entail on the structure of the animal changes of sufficient 

 importance to afford ordinal characters. 



Of the reduced Gasteropods we find their families esta- 

 blished on a diagnosis derived from the position and nature 

 of the breathing organs. Some can live and breathe in water 

 only, others only breathe the air ; and important modifica- 

 tions in the respiratory apparatus accompany these habits. 

 The distinguishing characters of the families then is superior 

 to that of the orders, — involving an error fatal to any sys- 

 tem. It is the same, but to a less marked degree, with the 

 distribution of the Trachelipods. They are first partitioned 

 into two suborders from the absence or possession of a fleshy 

 siphon, evidenced on the shell by its aperture being entire or 

 canaliculate or effuse ; and the character, as you may remem- 



