86 University of California Publications in Zoology 
and to Professors H. 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 eall 
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 deseription 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- 
