io Cincinnati Society of Natural History. 



d. Peridium sessile, but with a more or less thickened base. 



8. Calvatia. Peridium large, globose or turbinate, breaking up 

 into fragments from above downward, and gradually falling away: 

 threads of the capillitium very long, much branched and interwoven. 



9. Lycoperdon. Peridium small, globose, obovoid or turbinate, 

 membranaceous, dehiscent by a regular apical mouth, threads of the 

 capillitium long, slender, simple or branched. 



10. Bovistella. Peridium subglobose, membranaceous, dehis- 

 cent by a regular apical mouth; threads of the capillitium free, short, 

 several times dichotomously branched. 



e. Peridium sessile without any thickened base. 



11. Catastoma. Peridium globose, subcoriaceous, dehiscent by a 

 basal aperture ; threads of the capillitium free, short, simple, or 

 scarcely branched. 



12. Bovista. Peridium subglobose, membranaceous, dehiscent 

 by an apical mouth, or opening irregularly; threads of the capillitium 

 free, short, several times dichotomously branched. 



13. Mycenastrum. Peridium subglobose, very thick, coriaceous, 

 the upper part finally breaking up into irregular lobes or fragments ; 

 threads of the capillitium free, short, with a few short branches and 

 scattered prickles. 



I. Volvat.e. Outer peridium a thick, firm, persistent coat, at 

 first closely investing the inner peridium, then bursting above irregu- 

 larly, or splitting from the apex downward into several segments ; 

 inner peridium sessile, or with only a short pedicel or definitely stipi- 

 tate. Columella often present. 



Genus I. — Polyplocium, Berk. 



Volva ample, persistent, bursting irregularly ; stipe fibrous, con- 

 fluent with the peridium; inner peridium hemispheric, then expla- 

 nate, pileate, underneath gyrose-cellulose, at length splitting into thick 

 aculeiform processes. Capillitium of slender hyaline threads, scarcely 

 branched; spores subglobose, even, brown. 



Plants growing in sandy soil in warm and dry regions. The genus 

 is quite abnormal, being very closely related to the Agaricini, through 

 Montagnites ; the plants are very singular, and the early stages of their 

 growth do not appear to be known. 



1. P. inquinans, Berk. Volva cup-shaped, smooth, white ; stipe 

 thick, stout, tapering upward; inner peridium glabrous, by dryness 

 areolate ; spores ovoid, brown, 6-8 mic. in diameter. 



