Literary Notices. ix 



is distinctly difterontiated into lense and retinal portions, the line of 

 demarkation between them being distinct. 



The epiphysis consists of a curved cylinder of a composite char- 

 acter, the greater portion consisting of plexiform epithelium. Distallv 

 connected with the plexus is a vesicle which is composed of columnar 

 and, in some species, pigmented epithelium. The cavity of the vesicle 

 is stated not to be connected with infundibuliform proximal portion of 

 the epiphysis. Connective fibres pass from the vesicle to tHe parietal 

 organ. An immense blood sinus covers the epiphysis on the caudo- 

 dorsad aspect. 



Ritter concludes that the parietal organ is a degenerate eye, though 

 having no nervous connection with the brain. He thinks, however, that 

 the epiphysis may have secondarily acquired some function in connec- 

 tion with the lymph system. 



A very complete bibliography adds value to the paper. 



Brains of Dinosaurs. (^) 



Two points in the paper quoted are of interest to neurologists; 

 first, the new evidence as to the former functional condition of the 

 pineal eye, and second, the primitive condition of the brain. 



At the union of the squamosal and parietal bones there is a 

 median foramen which Marsh calls the "pineal foramen." It is the 

 same as the opening termed parietal foramen by other writers. " In old 

 individuals it is nearly or quite closed. When open it leads into a large 

 sinus, extending above the brain case into the cavities of the horn-cores. 

 This foramen has not before been observed in Dinosaurs." 



" The brain of 7'riccrafofs appears to have been smaller in propor- 

 tion to the entire skull than in any known vertebrate. The position of 

 the brain in the skull does not correspond to the axis of the latter, the 

 front being elevated at an angle of about thirty degrees. The brain- 

 case is well ossified in front, and in old animals there is a strong septum 

 separating the olfactory lobes." 



Even when compared with stegosaurus the brain seems of a low 

 type. The hemispheres are practically absent. An enormous fossa for 

 the reception of the hypophysis and a great development of the optic, 

 trigeminal and other cranial nerves are characteristics shown by 

 the casts. 



RECENT LITERATURE. 



Adamkeewicz, A. Die Arterien des Verliingerten IVIarkes vom 

 iibergang bis zur Briicke. Leipzig, 1S90. Freytag. 



I D. C. Marsh. The gigantic Ceratopsidse, or Horned Dinosaurs of North America. 

 Am. Journal '/Science, Vol XI. I, Feb., i89r. 



