86 University of California Publications in Zoology 



and to Professors IT. D. Reed, B. F. Kingsbury and W. A. 

 Hilton, of Cornell University, for their supervision and assist- 

 ance, as well as for the material used, and to Professor B. G. 

 Wilder for his helpful advice and the free use which he allowed 

 of the specimens in his neurological collection. 



The structure here described, which I shall provisionally call 

 the myelencephalic gland, was discovered while dissecting out 

 the brain of a long-nosed gar, Lepisosteus osseus. While dis- 

 secting away the cartilage bit by bit in the region of the hind 

 brain, there was noted a deeply pigmented mass of tissue lying 

 over the myelencephalon, and directly behind the cerebellum. 

 The first inclination was to tear this off with the cartilage and 

 dura mater as merely a pigmented mass of connective tissue, such 

 as often fills the subdural space in teleosts (see Wiedersheim. 

 1909, fig. 200, p. 294). Since, however, it was seen to have a 

 rather definite form, and to be in closer relation to the brain 

 than to any other part of the head, it was left in position, and 

 carefully dissected out with the brain, to the pial covering of 

 which it was firmly attached. 



Though many eminent and competent scientists have worked 

 over the brain of Lepisosteus, the myelencephalic gland seems 

 almost universally to have been overlooked. The only reference 

 to it which could be found in the literature on the brain of the 

 ganoids is by Herrick (1891). In his plate 13, figure 9, he 

 figures the dorsal aspect of the brain of Lepisosteus osseus, show- 

 ing the structure in question lying over the myelencephalon. 

 No reference is made to it in the text, and in the description of 

 the figure he merely says: "The bilobed mass lying behind the 

 cerebellum is not of a nervous character." But, as pointed out 

 by Wilder (1891), the membranous parieties of the brain are 

 an important morphological feature of the organ, and should be 

 considered in any treatment of the brain as a whole. As will 

 be shown later, the "bilobed mass" of Herrick is in direct con- 

 nection with the parieties of the brain, and therefore should not 

 be omitted from a morphological study of the brain because it 

 is not of nervous tissue. 



Parker and Balfour (1882) carefully worked out the brain 

 of the adult Lepisosteus, and demonstrated the delicate thin- 



