M6 Natural History of Molluscous Animals : — 



almost creative influence in framing or modifying animal 

 structures which many imagine they have ; for here are before 

 us a crowd of animals whose soft bodies, it will be allowed, 

 are as susceptible of changes, or of being moulded to one 

 type, as any animals can be, and the uniformity of whose 

 nervous system seems to prove that their faculties and desires 

 are much on a par ; yet, if we select any large family from 

 among them, we shall find them living in the same seas, and 

 in the same depths, and in the same latitudes, and on the 

 same food, and all breathing the same air ; but, so far from 

 showing a perfect agreement in their exterior organs, on which 

 these causes are said to operate so efficiently, we find all is 

 diverse, whether we look to the position, the form, or the 

 structure of the organs. These are now, my friend, such as 

 they were when the creatures came into existence from In- 

 finite Wisdom, perfect, and complete, and immutable, and, 

 notwithstanding all their variations, ever suited with special 

 adaptation to the element and the place they were foreor- 

 dained to inhabit. " Their forms are His special invention 

 and construction, and their principle of life is also His special 

 and communicated gift," is the just conclusion of a historian 

 eminently distinguished for his learning, his good sense, and 

 his piety.* 



Now, the distinction which has been drawn between the 

 Mollusca with lungs and gills, however anatomically correct, 

 is not always physiologically true ; for although I am not cog- 

 nisant of any pulmoniferous species that can breathe water, 

 or ever does so voluntarily, yet there are many branchiferous 

 ones that can and do respire the uncombined air. A great 

 number of bivalves are alternately submerged and exposed to 

 the air, according to the fluctuations of the tide ; but then the 

 concavity of the lower valve enables the animal always to 

 retain some moisture around its gills, and I believe they do 

 not open their shells freely unless when covered with water. 

 The Octopi of the cuttlefish tribe are said to come ashore 

 frequently, and live among the rocks for days together ; and 

 the Pteropoda and the naked Gasteropoda in general love to 

 swim at the surface in calm weather, particularly at the time 

 of sunset, apparently to enjoy the respiration of a lighter and 

 more oxygenated medium. There are other Gasteropoda 

 with gills which pass so large a portion of their term of life 



* Mr. Sharon Turner. His Sacred History of the World, from which 

 the quotation is taken, 1 earnestly recommend to the attentive perusal of 

 students of natural history. 



