18 



Mycologia 



At noon I decided to cross to the opposite hillside with its scat- 

 tered oaks of very large size. 



Under a single large tree on a very steep slope, I found a dense 

 mass of leafy humus overlying fine, loose, dry soil. I found a 

 few small Pezisas and was encouraged to look farther. When I 

 finished it was nearly sundown and not a foot of soil under that 

 tree had escaped search. On one side was the debris of a rat's 

 nest. The first find of importance was a few small, brown tubers, 

 at first referred to Tuber candidum, several specimens of Genea 

 arenaria, Hydnotrya ellipsospora, Hydnotryopsis Setchelli, and 

 some others. This was the first collection of truffles, and it now 

 seems that the brown tuber is an unreported species — certainly 

 not Tuber candidum, but I have not found it this season of 1918. 

 Many specimens were found both here and at the other location, 

 but very few contained mature spores. I also found them on 

 the coast side of the mountains. Genea arenaria is fairly well 

 known, and is well described by Dr. Gilkey in her Revision of the 

 Tuberales of California. Of Hydnotrya, but a single specimen 

 had been found in December, 1909, at Pacific Grove. During 

 the season I added nearly a dozen plants to the collection. Hyd- 

 notryopsis, likewise, was known only by very scanty material, but 

 Dr. Gilkey gave me personal assurance that material sent in that 

 day was sufficient to confirm her description in every detail made 

 from long preserved material in the Harkness collection. 



On April 15 I secured another tuber which promises to be in 

 a new genus close to Piersonia, according to Dr. Gilkey, but more 

 material must be had if possible. In a good collection made the 

 last of May and examined by Dr. Gilkey, there seems to be 

 another genus which she says is intermediate between Geopora 

 and Hydnotryopsis, but for the time being the specimens are re- 

 ferred to this latter genus. 



I have made frequent reference to the wood rats and their 

 nests, and it is well to explain that in many cases I have been well 

 rewarded by operating around them. The rotten wood and de- 

 composed material that settles around them seems tO' create ideal 

 conditions for growth of hypogaeous fungi. When one considers 

 the very large number of specimens taken in 191 7, as well as the 



