There are, notwithstanding; some shell animals, whose 

 structure, viih respect to its simplicity, seems to vie 

 ttith that of the polypus. 



Of this -number is the pond muscle, wherein we can 

 discover neither spinal marrow, arteries, veins, nor' 

 Rings; 



Does the scale of nature branch out as it advances ? 

 M',\v 5n c oot e ciuU shell-flsli be two parallel branches ^of 

 this great stem ] May the frog arid the lizard, which 

 bear. so near a resemblance to insects, be a ramification 

 of them ? We are not able, at present, to answer these 

 questions. 



Such -is the gradation between beings, that they often 

 differ from each other by slender shadowings ; and such 

 is the narrowness of our capacities, that none but the 

 flain, and more striking marks; attract our notice. 



18. The agreeable diversity in the figures of shells, 

 helps us to judge of the variety subsisting in the organi- 

 zation of those animals who are the inhabitants and ar* 

 chitects of tli em ; Some 1 consist of one entire piece ; 

 others, of two, or more. Sorne are formed in imitation 

 of a tntmpet. a screw, a tiara, a dial. Others resemble 

 a helmet, a club, a spider, a comb. In this, it is a kind 

 of fleshy case ; in another, it is a ship, wherein the sailor 

 is, at the same time, rudder, mast, and sail. 



Animals that have shells, and insects with scales, seem 

 to have an affinity to each other by a common charac- 

 ter; both of them have their bones placed on the out- 

 side. We may, in effect, consider the shell as the bone 

 of the animal which occupies it; since he bring, it into 

 the world- with him, and adheres to it by different 

 muscles. 



But it is certain, most shells are formed of the stony 

 juice?, which transude from the pores of the animal 



The bones, as well as the shells, of insects, grow, ?nd 

 are nourished, by vessels which pass through their 

 substance. 



E 4T 



