86 Notes on the Sori of Macrocystis and Postelsia. 



Bodega Bay, California. The plant which we have examined is in the 

 Herbarium of the British Museum, and was collected by Dr. Anderson 

 at Santa Cruz, California. The plant consists of a root-like member 

 bearing an unbranched, erect, hollow stem. The stem at its apex 

 divides into several portions, each of which bears directly, or after still 

 further divisions, a number of stalked fronds. 



The plant described and figured by Ruprecht presents some points 

 of difference ; the stem bears the stalked fronds directly from its apex 

 without any further division, and the fronds of his plant have a toothed 

 margin, and are larger than the smaller untoothed fronds of the specimen 

 we have examined. 



The fronds are longitudinally ribbed throughout their whole length, 

 the ribs being most marked in the central thicker portion of the thallus, 

 and diminishing in size towards the margins (plate XX., fig. 4.) The 

 epidermis of the frond consists of one or sometimes two layers of small 

 cells with coloured contents. Beneath this is the cortex, made up of 

 roundish thick-walled cells, of only a few layers in thickness in the 

 furrows, but forming the whole mass of the tissue of the ridges. The 

 medullary portion consists of filaments running in an irregularly longi- 

 tudinal direction forming a compact tissue. 



The fronds are all sporophylls, the sporangia occurring in the 

 following manner. At the points where the ridge bends into the furrow 

 the epidermal cells grow out into paraphyses, and the whole furrow is 

 lined with a dense mass of sporangia and typical Laminarian paraphyses 

 (plate XX., figs. 5 & 6). 



Ruprecht figures a transverse section of a frond showing the ridges 

 and furrows into which the thallus is folded ; he also describes and 

 figures the sporangia and paraphyses, but, in mentioning their position, 

 says only that they occur in patches near the apices of the mature 

 leaves. He does not appear to have noticed what has seemed a point 

 of interest to us, that, while throughout the whole frond the sporangia 

 occur regularly in the furrows, they never occur on the ridges of the 

 folds, a protection thus being afforded to them, by the natural structure 

 of the thallus, almost as perfect as that of a true conceptacle. 



A. LORRAIN SMITH. 

 FRANCES G. WHITTING. 



