THE ATRAMENTARIUS SUB-TYPE 261 



gills. In this respect we have a marked contrast with the Comatus 

 Sub-type in which the hymenium consists of basidia and paraphyses 

 only. 



(3) The interlamellar spaces between the gills, which are re- 

 quired to render possible the free development of the spores on the 

 hymenium, are secured by the cystidia acting as stays or distance- 

 pieces. Each cystidium is attached by its ends to two opposite 

 gills and therefore completely bridges the interlamellar space in 

 which it is developed. 



(4) The interlamellar spaces continue to be bridged by the 

 cystidia during the discharge of the spores. This character can be 

 recognised readily in the field and serves to distinguish the Atra- 

 mentarius Sub-type from all the other Coprinus Sub-types, 



(5) The basidia are dimorphic. They are of two lengths, long 

 and short. In this character there is an agreement with most of 

 the other Coprinus Sub-types but not with the Micaceus Sub-type 

 where the basidia are tetramorphic. 



Representative Species. — The Atramentarius Sub-type was 

 founded on Coprinus atramentarius, but it includes several other 

 species. Among these are the following : Coprinus picaceus, C. ster- 

 corarius, C. narcoticus, C. macrorhiztis, and C. urticaecola. All these 

 agree in having their gills compactly welded together into one 

 whole by innumerable bridging cystidia during spore-discharge ; 

 and they all differ, therefore, from the members of the other 

 Coprinus Sub-types, e.g. Coprinus micaceus, C. lagopus, etc., in 

 which the gills, owing to the expansion of the pileus, become quite 

 free from one another just before spore-discharge begins. 



Coprinus atramentarius. Preliminary Remarks on the Func- 

 tion and Fate of the Cystidia. — The central fact to bear in mind 

 in comparing the fruit-bodies of Coprinus atramentarius with those 

 of C. comatus and C. sterquilinus is that in C. atramentarius we have 

 what may be called the cystidial arrangement for separating the 

 gills, whereas in C. comatus and C. sterquilinus we have what may 

 be called the flange arrangerneyit. The cystidia provide one element, 

 and an important one, in a complicated mechanism which is so 

 constructed that through its operation the spores are efficiently 

 produced and efficiently liberated. As soon as the cystidia are of 



