172 FREDERICK TILNEY AND LUTHER F. WARREN 



by many authors in a number of mammals. Haller (1768) 165 

 considered it pathological, but Soemmering's 360 classical study 

 upon the acervulus clearly demonstrated that these concretions 

 are normal in man. Malacarne (1795) 258 found brain sand in 

 the epiphysis of the goat. Wenzel (1812) 420 described it in man 

 as being of two varieties according to its color, i.e., yellow or 

 white. Hagemann ('72) 164 considered it a normal constituent 

 of the adult pineal body in man. He also observed it in the ox. 

 Krause ('76) 218 found it in many adult mammals. Flesch 123 

 describes brain sand in the epiphysis of the horse, sheep, pig, 

 and dog. 



A parietal foramen has never been observed in mammals, but 

 the white spot which frequently appears in the frontal region of 

 the horse's head has been suggested as a vestigial indication of 

 this aperture in the skull seen in many of the lower vertebrates. 



Differences observed in the epiphyseal complex in the various 

 species of mammals already investigated. 



MARSUPIALS. 1. Macropus giganteus. Lotheissen ('94). 25 In 

 this species some nerve fibers penetrate into the substance of 

 the pineal gland. These come from the fasciculus retroflexus 

 of Meynert. 271 They were not observed in other mammals. 



2. Halmaturus'dorsalis. Condorelli-Francaviglia ('95). 70 In 

 this form, because of the rudimentary corpus callosum, the pineal 

 body extends dorsad between the hemispheres. Its length is 

 2 mm. and its thickness 1.5 mm. 



3. Didelphys virginiana. Jordan ('II). 198 In the opossum 

 the pineal body occurs in two forms, i.e., either as a long tubular 

 organ or as a short, cup-shaped structure. It is composed of 

 ependymal cells in a syncytial network. 



ARTIODACTYLA. 1. Bos taurus. Faivre ('55) ; 114 Hagemann 

 (72) ; i64 Chauveau ('85) 64 Nicolas ('00); 283B Dimitrova ('01) ; 92 

 Favaro ('04) ; 117 Constantini ('10); 7lA Cutore ('09). 74 In this 

 species the pineal body is cylindrico conical. Its diameters are: 



cm. 



Longitudinal 1.5 



Transverse 0.7 



Anteroposterior 0.7 



