1916] Yates: Ilistoloyy of Califonuan Bohiaccae 239 



siderably in tlieir diameter and in the length of the segments between 

 the septa. 



Ceriomyces communis, Form C 

 Plate 21, figure 1 



The phmts considered nnder Form C are rather larger than those 

 of Form B of Ceriomyces communis. The following description is 

 based upon fonr plants collected near IMill Valley, Marin County, 

 and filed under No. 240 in the Herbarium of the University of Cali- 

 fornia. The plants grew in dense shade under redwood {Sequoia 

 sempervirens), though not far from the margin of tlio woods where 

 there were individuals of Quercus agrifoUa. The pileus is 8 to 11 em. 

 in diameter, nearly flat, and the surface is brownish, tomentose, and 

 rimose. and divided otf into irregular areas 1 to 2 cm. across, separated 

 by deep cracks showing the yellowish context. The context, where 

 not exposed to the air, is white in color and does not become blue when 

 exposed to the air. Where the context is exposed to the air in the 

 cracks it is a light yellow. The tubes are long, yellow and do not 

 change to blue. The mouths are large and irregular. The stipe is 

 long (0 cm.) and slender (1.2 to 1.4 cm. in diameter), but in one indi- 

 vidual the base wa.s much larger. The surface of the stipe is red above 

 and \ellow below the middle. The context is white and does not 

 change to blue. 



Form C differs from all other forms of C. communis seen by the 

 writer in the deeply cracked surface of the pileas and the unusually 

 long, slender stipe. It differs from all our Californian plants referred 

 to C. communis, except Form E. in the unchanging color of the context. 



Histology 

 Examined under the microscope the surface of the pileus is found 

 to have a very characteristic surface layer. This rind is about 160 to 

 200// in thickness and is formed of hyphae united to form definite 

 tufts. These tufts are formed by the repeated dichotomous branching 

 of hyphal branches from the context. The hyphae making up these 

 tufts are 8 to 10/x in diameter, divided by cross partitions into cells 

 15 to 30|U, in length. The walls are yellowish brown in cohu- and are 

 pitted in a very characteristic fashion. Below the tufts, the hyphae 

 are 8/x in diameter and densely interwoven, passing gradually over 

 into the typical hyphae of the context, which are hyaline, with unpitted 

 walls qnd are repeatedly branched (pi. 23, fig. 19). 



