734 



ANATOMY OF VERTEBRATES. 



attached to part of the abdominal parietes, a, b, with the urinary- 

 bladder, q, the female organs, *, z, and rectum, p, o, of an aborted 

 foal. The membrane, d, d, is the amnios which was reflected from 

 the umbilical cord to inclose the foetus : the inner concave surface 

 of the bag, turned toward the parts of the foetus, is characterised 

 by the finely waved disposition of the amniotic vessels. Minute 



574 



Fetal niembraues, Equus. cxxn' 



filiform processes project from the serous surface of this part of 

 the cord. The urachus, accompanying the umbilical vessels 

 (one artery, two veins, b), opens, or expands, into the cavity of 

 the mucous layer of the allantois at e : this cavity is laid open, 

 showing the part of its wall reflected upon the exterior of the 

 amnios, at d d, and the part continued over the interior of the 

 vascular layer of the allantois, or chorion, at g g : a portion of its 

 exterior surface is shown at h. The umbilical vessels, continued 

 beyond the end of the urachus to the chorion, seem to form a 

 prolongation of the navel-string, about two feet in length, f, 

 between the amnios and the chorion, around which part of the 



