They are an Organ serving for Respiration, of a soft Substance, and porous as a Sponge, being all over beset with Arteries, Veins, Nerves, and Lymphatick Vessels, and perforated with small Cartilaginous Tubes, that are imparted to it from the Wind-Pipe, and are call'd _Bronchia_. Their Natural Colour is a pale Red, and marbl'd dark Brown; and their whole Body is wrapt up in a fine smooth Membrane, which they receive from the _Pleuron_. They are suspended by the Wind-Pipe, by their proper Artery and Vein, and by the Ligatures that fasten them to the _Sternum_, _Mediastinum_, and frequently to the _Pleuron_ it self: They are also divided into the Right and Left Parts by the _Mediastinum_; having four or five Lobes, whereof those on the Left side cover the Heart. Their continual Motion consists in _Inspiration_, to take in the Air, and _Expiration_, to drive it out. The _Larynx_ makes the Entrance of the Wind-Pipe {80} into the Lungs, and the _Pharynx_ that of the _Oesophagus_ or Gullet, at the bottom of the Mouth to pass into the Stomach. * * * * * CHAP. XV. _Of the Anatomy of the Head, or upper _Venter_._ _What is the head?_ It is a bony Part, that contains and encloseth the Brain within its Cavity. _What is most remarkable in the outward parts of the Head?_ The Temporal Arteries, the _Crotaphitæ_, or Temporal Muscles, and the Sutures of the Skull. _Why are these things considerable?_ The Temporal Arteries are of good Note, because they are expos'd on the outside, lying even with the Skin. The _Crotophite_ Muscles are so likewise, in regard that they cannot be hurt without danger of Convulsions, by reason of the _Pericranium_ with which they are cover'd. And the Sutures, because the _Meninges_ of the Brain proceed from thence to form the _Pericranium._ _What is the _Pericranium_?_ It is a Membrane that lies under the thick hairy Skin of the Head, and immediately covers the Skull. _What are the _Meninges_?_ They are two Membranes that enclose the Substance or Marrow of the Brain. _What is a Suture?_ {81} It is a kind of thick Seam or Stitch, that serves to unite the Bones of the Skull. _How many sorts of Sutures are there?_ There are two sorts, _viz._ the true, and the false or Bastard. _What are the true Sutures?_ They are three in number, namely the _Sagittal_, the _Coronal_, and the _Lambdoidal._ _What is the disposition or situation of the true Sutures?_ The _Sagittal_ is streight, beginning in the middle of the Fore-head, and sometimes at the root of the Nose, and being terminated behind, at the joining of the two Branches of the _Lambdoidal Suture_. The Coronal appears in form of a Crown, passing to the middle of the Head, and descending thro' the Temples, to finish its Circumference in the Root of the Nose. The _Lambdoidal_ Suture is made like an open Pair of Compasses, the Legs whereof are extended toward the Shoulders; and the Button is in the top of the Head backward.