STEMONITIS 165 



surface, the rest smooth, mostly 8-10 /x in diameter, but many larger, 

 clustered in groups of four or more, rarely single. 



The clustered spores and the loose surface net are the outstanding 

 characteristics of this species. Miss Lister speaks of a cap of minute 

 spines on the exposed side of the spores. This is scarcely adequate, as 

 the illustrations will show. 



Rare. District of Columbia, Pennsylvania, Montana, Washington. 



9. Stemonitis fenestrata Macbr. 



N. A. Slime-Moulds ed. 2. 166. 1922. 

 PL XI, Figs. 260, 261. 



1890. Stemonitis bauerlinii Mass. f. fenestrata Rex, Proc. Ac. Nat. Sc. Phila. 

 1890 : 37. 



Sporangia aggregated, in tufts 2 cm. or more in diameter, rich 

 purple-brown, on a common hypothallus, more or less erect, stipitate, 

 15-22 mm. tall, slender, triangular in section; stipe black, about one- 

 third the total height, passing into a slender columella which is lateral 

 in position, not central, but little branched, continued almost to the 

 apex; the capillitium consisting almost entirely of the peripheral net, 

 which presents meshes of unusual uniformity of size and shape; 

 spores dark in mass, pale brownish by transmitted light, spherical or 

 slightly elongated, 7-8.5 /a. Plasmodium probably white. 



The remarkable shape of the sporangium and the peculiar regularity 

 of the surface net, the lateral columella, all combine here to warrant 

 the erection of a distinct species. Doctor Rex referred this to S. bauer- 

 linii Mass. At that time he had not the author's description, and had 

 seen only a very poor fragment received with notes in a letter. 

 Mr. Massee's description makes it immediately evident that what- 

 ever other affiliations S. bauerlinii may have, by description it has at 

 least none with 5. fenestrata. Massee's species is described as having 

 the "mass of spores black," the capillitium with branches springing 

 from the columella, the main branches more and more numerous, 

 thicker, and irregular towards the apex of the sporangium, and often 

 forming irregular, flattened expansions. This suggests some form 

 of S. dictyospora Rost. Possibly for such reasons Lister referred it to 

 5. splendens Rost., which was undoubtedly regarded by the author 

 as belonging to the fusca group. 



The long, slender, simple columella is not only lateral, but occupies 

 the sharp vertical angle of the triangular, prismatic sporangium. 

 Furthermore, the sporangium is at maturity strangely twisted, so that 

 the columella in its ascent accomplishes one or more spiral turns. In 

 forms collected by Dr. Rex, which seemed to him most nearly to 



