220 DESCRIPTION of a 



S, The fpinal marrow. 



E. The cauda equina. 



i. 2. &c. to 16. Nerves fent off from the fpinal marrow in pairs. 



17. The os facrum. 



n. », The fciatic nerves. 



REMARKS on fuch Monsters. 



Monsters wanting the head, heart and lungs, and, in al- 

 moft every other refpecl, agreeing with that above defcribed, 

 have been mentioned by authors, particularly by Mery and 

 Winslow * , and the learned Dr Roederer f has given a full 

 defcription of a monfter, in which one fmall mufcular fac only 

 was found, inflead 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. 



Mery thinks the blood of the foetus mud have been moved 

 by the motion of the heart of the mother, and confiders the 

 want of the heart in fuch monflers, as a ftrong 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. 



f Aft. Got. t. iv. 1754. 



% Mery, Mem. de l'Acad. des Scien. 1720. ire 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 circule dans ce foetus ne 

 recevoit pas fon impulfion que du cceur 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. 



