12 LECTURE I. 



commonly called gills, in which innumerable divi- 

 sions of blood-vessels are disposed in semicircular 

 ranges. 



The third order or great division of animals 

 consists of such as Linnaeus supposes to have a heart 

 with a single cavity, and a cold whitish or nearly co- 

 lourless blood. These animals consist of Insects, and 

 of a very numerous and diversified tribe, called, 

 iu a large acceptation of the word, by the name 

 of Worms. The former of these tribes, or that of 

 Insects, is distinguished by the particular organs 

 called antennas, and resembling small horns ; while 

 the latter tribe, or that of Worms, is distinguished 

 by having tentacula or flexible feelers. Modern 

 observations seem to prove that the former of 

 these divisions, or Insects, have, in reality, no true 

 or regular circulation : this however is a point 

 which I confess I consider as by no means com- 

 pletely ascertained. 



Since the establishment of the Linnaean arrange- 

 ment, so captivating appears to have been the 

 study of system- making, that numerous arrange- 

 ments have been attempted in different parts of 

 the animal kingdom; more particularly within a 



