( »57^ ) 
., I, ivi ni 'ill 
II. A Letter to Dr Edward Tyfon. 
Gtying an Acconnt of the Anatomy of thofe parts of a 
Male Opoflum that differ from the Female. !Bji 
William Co wper, F. %S. 
HAd your Account of the Female OpoJJUm been lefs 
Accurate, I Ihouid not have been tempted to look 
farther than the Parts that diftinguifh the Sexes 5 for on 
<:om paring your Defeription of the Organs common to 
both, it was fufficiently evident how little can be added, 
tho you had but one Subjeft to examine. 
The lingular eontriyances of that Animals Organs ren- 
ders the Anatomy of them very dcfirable, I may fay 
entertaining, to thofe who have Taflcs for fuch enquiries. 
Omparative Anatomy ( as inftruftive as it is ) does not 
cfcape the Cenfure of the Vulgar ^ tho you know the 
greateft Illuftrations of the u(e of Parts are not only to 
be had from thence, but. the very cxiftence of divers 
Organs in Human Bodies have been made known to us 
by bifcoveries firft made in the Bodies of Quadrupeds. 
The Circulation of the Bloud, and the Paflages for the 
Chyle and Ljmpha^ had been as litik known to us as 
our Predeceflbrs, were it not for Difleftions made on the 
Bodies of fevera! Animals. But I fhall no more abufe 
your Patience M^ith^thefc kind of Apologies, than I would 
omit owning an obligation incumbent on me, (whtcb is) 
to beg your pardon tor making an attempt, where you 
have given fuch inftancts of your great Ability. 
This 
