220 DESCRIPTION Of a 
S, The fpinal marrow. 
E. The cauda equina. 
2. 8c. to 16. Nerves fent off from the fpinal marrow in pairs. 
4 The os facrum. 
n,n, The fciatic nerves. 
REMARKS on fuch Monsters. 
Monsters wanting the head, heart and lungs, and, in al- 
moft every other refpect, agreeing with that above defcribed, 
have been mentioned by authors, particularly by Mery and 
Winstow *, and the learned Dr ROEDERER + has given a full 
defcription of a monfter, in which one fmall mufcular fac only 
was found, inftead of a complete heart, communicating with 
the continuation of one of two veins which were found in the 
umbilical cord ; but the real courfe of the blood, or the caufes 
of its motion, appear to have been mifapprehended by all thefe 
authors. 
Me_ry thinks the blood of ale foetus muft have been moved 
by the motion of the heart of the mother, and confiders the 
want of the heart in fuch monfters, as a {trong confirmation of 
the opinion he entertained, that there is a circulation of the 
blood carried on between the mother and the foetus {. 
As 
* Mem. de l’Acad. 1720 and 1740. 
+ AG. Got. t. iv. 1754. 
{ Mery, Mem. de l’Acad. des Scien. 1720. 1te Reflexion. ‘‘ Sa vie n’a pu avoir 
pour principes que la refpiration et le mouvement circulaire du fang de fa mere.”” And _ 
in the Hiftoire, “‘ Le defaut du cceur prouve que le fang qui a circulé dans ce foetus ne 
recevoit pas fon impulfion que du coeur de mere.”” M. Mery a toujours foutenu la cir- 
culation reciproque entre la mere et le foetus, et telle que le foetus eft toujours comme 
un membre de la mere. 
