10S Khodora [May 



but distinct trigones. The underleaves are even more (lecurrent than 

 in P. platypkyUa and the decurrent portions tend to be more strongly 

 toothed. In other respects the underleaves are much the same in the 

 two species, although in M. Cordacana they are distinctly narrower, 

 being only a little wider than the stem. 



The female branches, which bear a single pair of bracts, sometimes 

 arise directly from the stem and sometimes from a primary branch. 

 In most eases, especially when the branch springs directly from the 

 stem the contrast in size between the bracts is very marked, the inner 

 bract being much larger than the outer. In the outer bract the lobule 

 is narrower than the lobe but almost equals it in length; in the 

 inner bract the lobe tends to be longer and broader than the lobule, 

 although it is always distinctly smaller than the lobes of ordinary 

 leaves. With respect to the apices of the lobes and lobules there 

 is much variety. The lobe of the inner bract, however, is usually 

 rounded at the apex, while the lobe of the outer bract and the lobules 

 of both bracts are usually more or less sharply pointed. The bracteole 

 is much the same as in related species. Both bracts and bracteole are 

 variously toothed, the teeth varying from slightly projecting cells to 

 cilia or broader teeth two to four cells long. The teeth are irregu- 

 larly scattered but tend to be closer together in the basal regions, where 

 they sometimes show vestiges of hyaline papillae. 



The perianth is especially remarkable on account of the character 

 of its mouth. In the other North American species of Porclla the 

 mouth is variously eiliate; in M. Cordacana it is subentire or vaguely 

 crenulate from projecting cells. Sometimes a slight lobing or indis- 

 tinctly sinuate appearance is present, but even then the mouth is very 

 different from what is found in other species. The sporophytic char- 

 acters arc much as in P. platypkyUa, the elaters being bispiral through- 

 out their entire length. 



In separating M. Cordacana from P. platypkyUa the subentire mouth 

 of the perianth, the large inner perichaetial bract, and the small and 

 long-decurrent lobules yield the most helpful characters. The mouth 

 of the perianth will likewise distinguish it from P. pinnata, although 

 there is now little danger of confusing these two species even when 

 sterile, on account of the blunt, entire, and transversely attached 

 lobules and underleaves in P. pinnata. 



Although M. Cordacana is not uncommon from the Rocky Moun- 

 tains westward very few stations from the eastern part of North 



