Dr. SmitH’s Introductory Difcourfe. | 19 
his own, although Willoughby is there often quoted for many ex- 
cellent obfervations; and the fame may be faid of the Hiftoria Infec- 
. torum, publifhed in 1719, after the death of Ray. All thefe works 
are excellent in their kind, admirably methodized, and exhibit fuch, 
proofs of accurate obfervation, fuch a candid love of truth, and fuch 
penetration in difcovering it, as muft ever rank their authors among 
the firft and moft philofophical naturalifts. 
Ray, being diffatished with Ariftotle’s claffification of animals, 
was the inventor of a new one, founded on the ftruéture of the 
heart. "The Harveian experiments and doctrine of the circulation, 
had called the peculiar attention of philofophers to every organ 
which has a fhare in that phenomenon, and to this caufe probably 
we owe the method of Ray. Taking therefore the divifion of ani- 
! zuln id Exanguia, which was a very ancient one, 
he fabdivides arg fit san into fach as are furnifhed with lungs 
and fuch as breathe by gills; and the former of thefe he again 
feparates into thofe which have an heart with two ventricles, and 
thofe whofe heart has only a fingle ventricle. The latter divifion 
contains Reptiles, the former viviparous Quadrupeds, Whales and 
Birds, The Animalia branchiis refpirantia include all Fifhes pro- 
perly: fo called, the Whale kind and all the Exanguia being of 
courfe excluded. "The Animalia Exanguia are divided into greater 
and leffer. The latter divifion contains Infects; the former is again 
fubdivided into three genera, the firft of which includes the Mollia, 
or Mollufca, as Cuttle-fifh and Polypi; the fecond Cruftacea, as 
Crabs and Lobfters, which are properly Infeéts ; and the third Tef-. - 
tacea, or fhell-fifh. This fyftem, although liable to agreat many- 
objections, which I fhall not now ftay to enumerate, is deferving in 
many refpects of great praife: its author has fhewn great fkill in. 
the characters by which he has chofen to difcriminate the fubordi- 
nate divi and in fhort the Linnzan fyftem of Quadrupeds is 
D 2 | little 
