4. =Dura.= Collections of pus may be found between skull-cap and dura in purulent inflammations of scalp or diploë. Rupture of middle meningeal artery or its branches, with or without fracture of the skull, gives rise to hemorrhagic extravasations in same location. Old hemorrhages may be partly organized. In young infants the dura is adherent to the skull-cap and cannot be separated. In youth and adult life it is adherent only along the longitudinal sinus and about the blood-vessels; in old age it becomes more adherent. Extent, location and strength of adhesions should be noted. The normal dura should be grayish-red, smooth, symmetrically stretched, so that a small fold only can be taken up by the fingers in the frontal region, and just translucent enough to show the outlines of the convolutions and the pial vessels. An increased tension is caused by exudates, tumor, abscess, hydrocephalus, hemorrhage, congestion, œdema, etc. Diminished tension occurs in atrophy of the brain, especially marked in the frontal region, where the dura may be wrinkled and loose. Perforations of the dura by Pacchionian bodies are very common along the longitudinal sinus in late life, and should not be regarded as pathologic. Small osteomata are not uncommon in the same place and in the falx; they may be very numerous in acromegaly, late syphilis and cachectic conditions. Changes in the color of the surface of the dura may be due to hemorrhage, purulent or syphilitic inflammation, old thickenings, etc. Thickenings are more easily seen from the inside surface of the dura; they appear as hard, tendon-like, opaque areas. The normal inner surface is smooth, grayish and moist-shining. In pachymeningitis it may be dry, dull, roughened, and covered with blood, pus or fibrin. The most frequent pathologic condition on the inside of the dura is the organizing or encapsulated hemorrhage (pachymeningitis hæmorrhagica chronica, hæmatoma duræ), so common in chronic alcoholics. Miliary tubercles of the dura are common in meningeal tuberculosis. A gummatous pachymeningitis is not infrequent in late syphilis. Pachymeningitis fibrosa is also common in old syphilitics. Actinomycosis occurs in connection with actinomycotic encephalitis. The primary tumors of the dura are fibroma, osteoma, fibro-endothelial tumors (psammoma) and angiosarcoma, etc. Secondary carcinoma or sarcoma is rare. 5. =Longitudinal Sinus.= Character of walls and contents. Thrombosis, with purulent or gangrenous inflammation, is the most important condition. Note mouths of superior cerebral veins. 6. =Meningeal Vessels.= Note grooves, rupture, thrombosis, hemorrhage, infection, amount of blood, symmetry of distribution, etc. Traumatic rupture of middle meningeal is the most important condition.