498 ~ 
scribed them as ‘white circular depressions.” This was about 
all that was known concerning these structures at that time. 
Acharius was the first to introduce the term cyphellae, which term 
has been retained up to the present. Since these organs are little 
known, it will be well to describe them more in detail. 
The cyphellae occur almost exclusively in the genera Sécta 
and Stictina and are primarily breaks in the continuity of the 
lower cortical layer. The hyphae of the medullary layer immedi- 
ately about the opening in the cortical layer divide more fre- 
quently, producing a dense net-work of hyphae or evena semicor- 
tical structure. As a rule, the cells of this secondary cyphellar 
formation extend in a direction at right angles to the outer sur- 
face; that is, they assume a suitable position for the conduction 
of food-substances. The margin of the primary cortical layer (the 
cortical layer of the thallus) is turned more or less outward. As 
a rule the algae of the algal layer immediately over the cyphellar 
opening multiply more rapidly, this causing them to accumulate 
at these areas. 
Two kinds of cyphellae may be recognized. Form 1, as 
seen in Svictina damaccornis. The cyphellar depression is usually 
circular, concave inward, the margin of the cortex forming an 
outer constriction. The broken-down cortex of the thallus is 
replaced by the secondary semicortical formation of the medullary 
hyphae. Its outer surface is usually smooth, devoid of rhizoids, 
and generally of a paler color than the primary cortical tissue. 
They are irregularly distributed over the elevated portions of the 
lower surface of the thallus; none ever occur in the grooves. 
They appear first in the older portions of the thallus. In form 
they are quite constant, in size they decrease toward the younger 
portion of the thallus. : 
Form 2, as seen in the majority of Sé#ctas and Stictinas. It is 
much more common and differs from the former in the absence of 
the formation of a secondary semicortical cyphellar covering. 
Instead of a depression as in the former case, there is usually a 
protrusion of the densely interwoven network of medullary 
hyphae. Their form is usually less regular. Their position 
and arrangement is the same as in the first form. 
Both forms of cyphellae are sufficiently large to be seen by 
