NERVOUS SYSTEM. VEUTEBUATA. 



D. 733. The choroid plexus of a Porpoise (/>h,-fi>napkoeana). 



The choroid plexuses are ]>lr;.te,l invari n! m.m* of lh<i 

 anterior and posterior tela choroidea into the 1;. 

 fourth ventricles of the brain. They oonsid of highly 

 vascular pia mater covered on its inner surfaee l,y the 

 columnar epithelium that lines the brain cavities, 'i 

 are mainly concerned in the production of the cvrebro- 

 spinal fluid. O. C. 1334. J/unterian. 



D. 734. The choroid plexus of a Piked Whale (Balwnoptera 

 acuto-rostrata) . 0. C. 1337. Hunterian. 



D. 735. The head of a small American Monkey (Callithru; >p.) 

 from which the calvarium has been removed, leaving the 

 external surface of the dura mater exposed to view. The 

 outer parts of the dura are closely applied to the cranial 

 bones and form their periosteum. The arteries have been 

 injected. O. C. 1345 A. 



D. 736. A vertical section of the head of a young child, showing 

 the processes of the dura mater that project into the cranial 

 cavity and support the several regions of the brain. Th- 

 are: the falx cerebri an extensive sagittal partition 

 between the upper parts of the hemispheres ; the tentorium, 

 crossing the hinder part of the cranial cavity in a trans- 

 verse and obliquely horizontal direction and situated 

 between the jcerebrum and cerebellum ; and the falx 

 belli, a small sagittal partition lying between the hemi- 

 spheres of the cerebellum. The transit of the crauial 

 nerves through the dura mater at the base of the cranium 

 is also shown. The proximal ends of the straight and 

 superior longitudinal sinuses have been exposed by the 

 section, and a black bristle has been inserted into the 

 superior longitudinal sinus. Black bristles have been in- 

 serted into the optic foramen and into the cavity of the 



O.C.1344A. 



D. 737. The dura mater removed from the dorsal parts of a 

 human brain, showing the falx cerebri and the parts of the 



> i -J 



