MacMillan: OBSERVATIONS ON PTERYGOPHORA. 739 
I desire to express my thanks to Miss Josephine E. Tilden 
for the winter fruiting material which she kindly collected for 
me and for the series of slides from which most of my descrip- 
tion has been made, and to Mr. H. L. Lyon for the photo-mi- 
crographs reproduced in plate LXI and prepared by him at 
my request. 
SUMMARY. 
1. Pterygophora californica grows to a larger size than 
generally known. Specimens ten feet in length with trunks 
three inches in diameter have been seen. 
2. As displayed in the Straits of Fuca, Pterygophora is a 
surge plant, growing below the zone of Lessonza and above 
that of Vereocystis. 
3. Pterygophora may be classified either in the Laminariez 
or the Alariidee. Its characters are in many respects inter- 
mediate between these tribes. 
4. The holdfast shows distinct rings of growth and these in 
most instances arise, not through morphological differences be- 
tween adjacent cell-layers, but through differences in the cell 
contents. The substances, which produced in greater or less 
amount give the ringed appearance, are regarded as polysac- 
charids allied to mucine, as described by Koch. 
5. The stipe is devoid of the mucilage ducts of Ruprecht and 
shows distinct rings of growth, due in most instances, to the 
juxtaposition of a layer of cells with larger lumina, upon a layer 
with smaller. In some cases the ringed appearance of the stipe 
seemed to be due to the same condition described for the holdfast. 
. 6. In the cortex of the lamina large polysaccharid idioblasts 
are abundantly developed. These are most numerous in the 
pinne and are often exhausted of their contents during the proc- 
ess of soral formation. 
7. The sori are distributed in irregular patches toward the 
base of the pinna and in the disposition of the cuticular caps 
upon the paraphyses suggest Lessonza. The plant fruits in the 
latitude of Port Renfrew during the month of December. 
DESCRIPTION OF PLATE LVII. 
Young plants of Pterygophora, about one-half natural size. 
eo) Plant ‘+ A.” of-text. 
2, 3, 4. Somewhat older plants; in 4 the midrib is just beginning 
to appear in the base of the lamina. 
