342 THE DUCTLESS GLANDS [CH. XXIII. 



quadrigemina. It is composed of tubes and saccules lined and some- 

 times filled with epithelial cells, and containing deposits of earthy 

 salts (brain sand). These are separated by vascular connective tissue. 

 A few small atrophied nerve-cells without axons are also seen. 



In certain lizards, such as Hatteria, the pineaj gland is better 

 developed and is connected by nerve-fibres to a rudimentary third 

 eye situated centrally on the upper surface of the head, but covered 

 by skin. 



The Coccygeal and Carotid Glands. 



These so-called glands are situated, the one in front of the tip of 

 the coccyx and the other at the point of bifurcation of the common 

 carotid artery on each side. They are made up of a plexus of small 

 arteries, and are enclosed and supported by a capsule of fibrous tissue. 

 They contain also polyhedral cells collected into spheroidal clumps 

 (carotid gland) or irregular nodules (coccygeal gland). Some of the 

 cells of the carotid gland stain brown with chromic acid like those of 

 the supra-renal medulla. 



