484 PHYSIOLOGICAL SERIES. 



tentorium in connection with it. The straight sinus and 

 proximal parts of the lateral sinuses have been opened from 

 below, the walls of the former being kept apart by a hlaek 

 bristle. Other bristles have been inserted between ibe layers 

 of the falx cerebri and into a cavity beside the superior 

 longitudinal sinus, tbe cut end of which is >ituated just 

 posterior to the right lateral sinus. A similar opening- 

 can also be seen upon the left side. In this specimen the 

 arteries are injected. O. C. 1344. 



D. 738. A portion of the dura mater from the dorsal parts of a 

 Human cranium. Its fibrous nature is clearly shown. The 

 -nperior longitudinal sinus has been laid open to show a 

 number of " glandulse Pacchioni " irregular outgrowth; 

 of the arachnoid membrane, through which the cerebro- 

 spinal fluid contained in the sub-arachnoid space can exude 

 into the blood. 



The two layers of the dura mater have been separated 

 and a portion of the external laver removed from one side. 



0. C. 1345. flunter'nin. 



D. 739. The brain of a Human Female covered bv the pia mater 

 and arachnoid membranes. 0. 0. 1339. /htnterian. 



D. 740. A portion of the pia mater with the arachnoid membrane 

 adhering to it, from one of the cerebral hemispheres of a 

 Human brain. The pia mater is thrown into a aeries of 

 folds, that pass between the convolution- of the brain, and 

 >upport the blood-vessels in their progress to the deeper 

 parts. The villous character of the inner surface of this 

 membrane i- produced by the minute yesselfl which, adher- 

 ing to the pia mater, have been torn from the cerebral 

 HiUtance. The arachnoid membrane is extended smoothly 

 Over ill*- external -ill-face of the pia mater, attached to it 

 bv numerous delicate lamin;e and trabecula'. but i- nd 

 reflected with it into the sulei of the hemisphere. The 

 arterie- in thi> .-pceimcn have been minutely injected. 

 The external .-urface of the arachnoid membrane i- -inooth 

 and is separated ly a slight cavity from the dura mater. 



O.C. 1343. JIu,,l,i-mn. 



