American Species of Marchantia. 263 



is distinguished from M. polymorpha by its somewhat smaller 

 size, by its total lack of epidermal papillae, by having the pores 

 bounded by six or seven rows of cells, by the presence of 

 s'clerotic cells, by the flattened rays of the female receptacles, by 

 the lack of marginal scales and by marked differences in the 

 appendages of the" median scales. In M. polymorpha epidermal 

 papillae are always present on cupules and female receptacles, 

 the pores are surrounded by only four or five rows of cells, there 

 are no sclerotic cells, the rays of the female receptacle are terete, 

 and marginal scales are always present. 



The features of the appendages in AI. paleacea deserve par- 

 ticular attention (Fig. 7, B-L). When a long series is 

 examined, it will be seen that they exhibit marked differences 

 in their apices and margins, although they are almost constantly 

 longer than broad and maintain an oblong or ovate form. The 

 apex is sometimes rounded, sometimes truncate, and sometimes 

 apiculate or even acute, while the margin may be entire through- 

 out, variously toothed, or even provided with a basal lobe. A 

 tooth, on its part, may be the slightest and vaguest projection 

 of a marginal cell, it may be a distinctly projecting cell, or it may 

 consist of a cell borne on a stalk-cell; in some of the broader 

 teeth two adjoining cells may even be involved. It must be 

 admitted, however, that large and complicated teeth are the excep- 

 tion. In commenting on the type specimen of M. nitida Schiff- 

 ner states that the appendages are broadly ovate, less pointed at 

 the apex and scarcely toothed, those of his Javan material being 

 broadly cordate, abruptly pointed and with irregular and distant 

 marginal teeth. These differences, which he considers of little 

 importance, are shown by Fig. 7, J, L, and at first sight are 

 somewhat striking. Since, however, equally extreme conditions 

 are sometimes found on a single specimen, as shown by Fig. 

 7, G, H, it is evident that Schiffner did not underrate their 

 value. The appendages also vary in the number of cells with 

 oil-bodies which they show. In some cases no such cells are 

 present ; in one case as many as ten were counted ; in the 

 majority of cases there are from one to three. The gradual 

 decrease in size between the median cells and the marginal cells 

 is usually evident, although the actual measurements are not very 

 different, and a distinct margin is never apparent as in M. 

 Berteroana. It may be noted that Stephani assigns smaller mar- 



