In the upper and hinder-part of the Hole, from whence the lateral Sinus's issue forth, is to be seen an opening in the Extremity of a Ductus, the Mouth whereof lies behind the Condyli, which are on the sides of the Occipital Trunk: This Ductus is extended about the length of two Hairs breadth in the Bone, and the Canal enclos'd therein is open'd immediately into the Vertebral Sinus: So that one might affirm it to be as it were its Original Source. Whence it appears that the Blood contained in the lateral Sinus's is emptied thro' two places; the greater Portion thereof descending in the Jugulars
from the Neck, and the other in the Vertebral Sinus's: Sometimes those Ductus's are four only on one side, another while both are stopt up, and the Blood contain'd in the lateral Sinus's is discharg'd into the Internal Jugulars.
Behind the Apophysis Mastoides on each side is a remarkable Hole, thro' which passeth a thick Vein, which brings back part of the Blood that hath been distributed to the Teguments and Muscles, which cover part of the Occiput or hinder-side of the Head: This Vein is open'd into the lateral Sinus's at the place where they begin to turn about. But in the Heads of some Persons, this Hole is found only on one side, and even sometimes not at all, in which case the Blood contain'd in the Vessels falls into the External Jugulars, with which the Branches of this Vein have a Communication.
In each Parietal Bone on the side of the Sagittal Suture, at a little distance from the Lambdoidal, appears a Hole, thro' which passeth a Vein, that brings back the Blood of the Teguments of the Head, and dischargeth it self into the upper Longitudinal Sinus. These Holes are sometimes on both; and then the Blood contain'd in the Branches of this Vein runs into the External Jugulars.
In the middle of the Sella of the Os Sphenoides, we may observe one or two small Holes thro' which (according to the Opinion of some Modern Anatomists) the Lympha contain'd in the Glandula Pituitaria is thrown
into the Sinus of the edge of the Os Sphenoides; nevertheless it is certain, that these Holes are fill'd only with Sanguinary Vessels, which carry and bring back the Blood of the Bones and Membranes, whereof those Sinus's are compos'd; besides that, these Holes are rarely found in adult Persons.
Between the Spine of the Coronal Suture and the Crista Galli, is a Hole which serves as an Entrance for a Ductus, which sinks from the top to the bottom, the length of about two Hairs breadth in the thickness of the inner Table of the Coronal: The Root of the upper Longitudinal Sinus is strongly implanted in this Hole, which also affords a Passage to some Sanguinary Vessels appointed for the Nourishment of this inner Table.
Many other small Holes are found in divers places of the Basis of the Skull; the chief whereof are those that are observ'd in the Apophysis Petrosa, and give Passage to a great number of Vessels that serve for the Nutriment of that part of the Temporal Bone which is call'd the Tympanum, or Drum: The other Holes are principally design'd for the Vessels that are serviceable in the nourishing of divers parts of the Basis of the Skull.
After what manner is the opening of the Head or Skull perform'd?
It is done by sawing it asunder round about and above the Ears; then it is taken off, after having before cut off the Hair, and made a Crucial Incision in the Skin from the fore-part to the hinder, and from one Ear to the other; as also after having