fluence to secure the work. It costs one hundred and eighty francs 

 per series of one hundred plates.f and the intention was to issue a 

 series each year for six years. The only adverse criticism I have 

 ever heard offered concerning the work is that the plates are expensive. 

 They may be expensive, but certainly the price can not be called ex- 

 cessive when the plates are sold at less than the cost of production, and 

 surely plates of this quality can not be published more cheaply when the 

 artist donates his services as a labor of love. If he were paid a fair 

 price for his work the plates could not be sold lor ten times the 

 present price. Aside from their scientific value, these plates merit a 

 place in the art department of every library that maintains an art 

 room, and it is to be hoped that at once twenty-one individuals or 

 libraries will subscribe for the set, thus insuring the completion of the 

 work. 



Subscriptions should be sent to Monsieur Paul Klincksieck, 

 3 rue Corneille, Paris, France. 



THE GENUS ARACHNION. 



The ideas of the genus Arachnion are derived from the ripe spec- 

 imens. In these the spores are found to be collected in little balls, 

 called peridioles, which are surrounded by a few, loose, hyphae 

 threads. In the usual American form these threads are relatively 

 numerous, and the peridioles are likened to little sacks. I think the 

 idea is a little overdrawn, for the threads form a loose network at the 

 best, and never I think a true membrane. 



In addition, in a new form that has just reached us from Austra- 

 lia, the spores are collected in little, irregular masses with very few 

 surrounding threads, almost naked in fact. And to complicate the 

 question, plants have recently been discovered in Texas and Mexico 

 which we place in another genus, Holocotylon, because the spores are 

 not collected in little, separate masses, but the entire contents of each 

 peridium consist of spores lining irregular and confluent cells, and 

 forming a continuous mass of gleba. The genus Holocotylon is so 

 close to Arachnion in its general nature and habits that it is a ques- 

 tion if it were not better to consider it as an Arachnion and to extend 

 the limits of that genus to include it. 



The genus Arachnion hasalwaysa very thin peridium with a smooth 

 cortex. It breaks irregularly and is so fragile that it is difficult to keep 

 entire ripe specimens in the herbarium. There is no sterile base. 

 The gleba consists of little granular masses of spores called perid- 

 ioles which in the type species are each surrounded with an imperfect 

 web of hyphae, analagous to the capillitium of other "puff-balls" 

 and for convenience called capillitium. In Arachnion rufum, of 

 Australia and in a form of Arachnion album from Brazil the peridioles 

 are almost devoid of hyphae, almost naked, little balls of spores. The 

 spores are borne on slender sterigmata which in some specimens . not 



t See correction, page 259. 



2 5 2- 



