398 E. A. BAUMGARTNER 
polyhedral cells contain small spherical nuclei. The cytoplasm 
is granular and stains deeply. 
Pettit (06) made a study of the hypophysis in Centroscymnus. 
He mentioned posterior, median and anterior parts, all com- 
municating. He found ramifying cords or tubules surrounded 
by sinusoids. 
Burekhardt (07, 711) in his work on the central nervous 
system of selachians described, incidentally, the hypophysis in 
Seymnus. He recognized a terminal, a median and a posterior 
lobe. Apparently he included under his division of median 
lobe, the caudal end of the anterior lobe of Sterzi, or it may be 
that the hypophysis in Scymnus is quite different from that 
found in other forms. . 
Joris (’08, ’09) described the dorsal lobe in Spinax and Mus- 
telus as formed in part from the hypophyseal evagination and in 
part from the infundibulum. The cell cords arise from the 
hypophysis while neuroglia and nerve fibres from the infundib- 
ular region grow in between these. 
In 1909 Sterzi in his comprehensive work on the central 
nervous system of selachians, gave a clear description of the 
hypophysis. According to this description the hypophysis is 
composed of perimeningeal and endocranial parts. The peri- 
meningeal portion is further subdivided into a dorsal and a 
rostral lobe. The dorsal lobe has many columns from its dorsal 
surface. Among these are numerous capillaries. The rostral 
lobe is a long flattened part extending almost to the optic chiasma. 
The endocranial part is composed of two sacs connected medially 
to one canal which leads to the anterior or rostral lobe. The 
cords and tubules of the dorsal lobe anastomose forming a net- 
work in which is a rich vascular supply. These are primarily 
attached by means of connective tissue to the base of the brain 
or vascular sac. ‘The structure of these cords, Sterzi had de- 
scribed before (04). The dorsal lobe, because it stained so lightly 
he termed the chromophobic portion. The rostral lobe has 
tubules extending from its ventral walls. The ventral wall has 
a distinct median ventral furrow and the tubules of either side 
