524 



THE PHILOSOPHY 



When examining the charadters by which beings are diftinguifh- 

 able from each other, we perceive that fome of them are more ge- 

 neral, and include a greater variety than others. From this cir- 

 cumftance all our diftributions into clafles, orders, genera, and fpe- 

 cies, are derived. Between two clafles, or two genera, however. 

 Nature always exhibits intermediate produdlions fo clofely allied, 

 ihat it is extremely difficult to afcertain to which of them they be- 

 long. The polypus, which multiplies by fhoots, or by feftions, 

 from its body, conneds the animal to the vegetable kingdom. Thofe 

 worms which lodge in tubes compofed of fand, feem to link the in- 

 feds to the fhell and cruftaceous animals. Shell-animals and crufta- 

 ceous infe£ts make alfo a near approach to each other. Both of 

 them have their mufcles and inftruments of motion attached to ex- 

 ternal inftead of internal bones. From reptiles, the degrees of per- 

 fedion in animal life and powers move forward in a gradual but 

 perceptible manner. The number of their organs of fenfe, and the 

 general conformation of their bodies, begin to have a greater ana- 

 logy to the ftrudture of thofe animals which we are accuftomed to 

 confider as belonging to the more perfedl kinds. The fnake, by 

 its form, its movements, and its mode of living, is evidently con- 

 neded with the eel and the water-ferpent. Like reptiles, moft fifh- 

 es are covered with fcales, the colours and variety of which oftea 

 enable us to diftinguilh one fpecies from another. The forms of 

 fifties are exceedingly various. Some are long and flender ; others 

 are broad and contradted. Some fifties are flat, others cylindrical, 

 irlangular, fquare, circular, &c. The fins of fifties, from the me- 

 dium in which they live, are analogous to the wings of birds. Like 

 thofe of reptiles, the heads of fifties are immediately conneded to 

 their bodies, without the intervention of necks. The flying filhes^ 

 whofe fins referable the wings of bats, form one link which unites 

 the fifties to the feathered tribes. Aquatic birds fucceed, by a gentk 

 gradation, the flying fifties. 



In 



