1916J Yates: Histology of Californian BoJetaceae 223 



Peck, 1889, writing upon the Boleti of the Fnited States, lists some 

 one hundred and ten species in three genera as follows : Boletus, one 

 hundred and three species; Boletinus, five species; and Strohilomyces, 

 two species. He also includes a few forms which he does not definitely 

 place. 



As defined by Peck, tiie genus Bold us includes all forms in wliich 

 the tubes separate readily from each other and from the pileus. The 

 forms in which the tubes do not separate readily he placed in the 

 two genera Boletinus and Slrohilomyces, according to whether there 

 is a perceptibly radiating arrangement of the tubes or not. 



Peck further divided the genus Boletus, as he limited it, into eleven 

 subgenera or tribes, corresponding very closely to the subdivisions of 

 Fries. In fact. Peck's classification of the group is simply that of 

 Fries modified so as to meet American conditions. 



Hennings (1898), in his account in Engler and Praiill, Di< yatiir- 

 lichen Pfanzenfamilien, which has probably had great influence on 

 modern work along this line, names eight genera of Boletaceae, which 

 are placed as a .subfamily under the Polyporaceae. However, there 

 are probably only six of these genera which should be included in 

 the family as now characterized. The genus Henningsia admitted by 

 him. should probably be excluded, as suggested by Hennings himself, 

 since the fruiting body is sessile and tough. The genus Camphellia is 

 described as including forms with a fruiting body of gelatinous con- 

 sistency and is probably better placed with M( ridlns, as was also 

 suggested by Hennings. The remaining six genera appear to ])e 

 separated by very good characters, such as spore color, presence or 

 absence of a veil, and, in one genus, the presence of a volva. 



The latest American account, that of Dr. AV. A. .Miirrill (1!)10), 

 separates the Boleti from the Polyporaceae and raises tliciii to tlie rank 

 of a family. 



Dr. Alurrill has divided the Boletaceae into eleven genera and has 

 followed Peck rather closely in certain respects. ]\Iuri"i]l has retained 

 all of Peek's generic names and has raised several of the latter 's tribes 

 to generic rank. ^NFurrill bases his distinctions largely upon spore 

 characters and morphological characters which can be i-cadily recog- 

 nized even in dried material. In attempting to work (•vei- tiie ("ali- 

 foi-nian species .Murrill's generic distinctions have proved to be the 

 most satisfactory of any that we have at the present lime. 



In this publication (1910) Murrill lists seventy-Hve species as North 

 American, divided among the eleven genera as follow.s: Gyroporus, 



