320 BOTANICAL GAZETTE | NOVEMBER 
in the formalose preparation, but not so different in color inthe — 
fresh material. 
The laminae, of which over eight hundred are present upon 
the specimen under observation, vary in length from 10™ on 
weaker lateral branches to over a meter on the stronger and 
central branches. They are all ribbon-shaped, thin, and gradu- — 
ally attenuated to a point. Robust and well-developed laminae — 
measure from 5—6°™ across near the base, but many of them are ; 
scarcely 1™in diameter. Some of the leaves have very well — 
marked midribs, while others are quite devoid of them, and it — 
is the narrow leaves which are provided most constantly — 
with midribs, while the broader leaves commonly do not 
develop them. Through the dichotomy of the plant it generally | 
happens that two pairs of leaves are borne close together ; that 
is the laminae appear in groups of four, of which two may be 
described as inner and the other two as outer. All four of the — 
leaves may be of the slender type with midribs, or the two outer : 
leaves may be:broad and the two inner narrow. So far as this 
specimen shows, it is only upon the broad leaves without mid: 
ribs that sori of sporangia are produced. When the pee : 
present it is often very wide, reaching within 2™ of the ge . 
margin, but in many of the slenderer leaves the midrib 1s y q 
one third the diameter of the whole lamina. There is a differ- 
ence, too, between the broad and narrow leaves in thelt a 
the broad ones being often rounded, while the narrow ones ? 
attenuate. Sori, when present, form patches 10™ or more 7 
length on both sides of the broad-based sporophylls. — 
three such sori are found in succession upon larger pace ‘ 
bearing laminae, and give a somewhat blistered app 
the leaf, owing to the characteristic loosening of the . ay 
common to all Laminariacee. 
The presence of two kinds of leaves has been already 
in other members of the genus, and the explanation eae 
some instances has been that the leaves are bien ring the 
the first year they fail to produce sporangia, but later, . get 
second year of their life, sporangia are produced uP 
