American Species of Marchantia. 269 



being usually more than nine and scarcely if at all dilated at the 

 apex. In M. paleacea the stalk of the female receptacle shows 

 only two rhizoid-furrows, and the disc is more deeply divided, 

 the lobes being usually nine (or fewer) and more or less 

 distinctly dilated at the apex; the upper surface of the disc, 

 moreover, shows a median protuberance and nine ridges cor- 

 responding with the rays, these structures being very indistinct 

 in M. hreviloha or absent altogether. In M. hreviloha the cupula 

 is simply short-ciliate ; in M. paleacea it shows a series of ciliate 

 or dentate lobes. 



There is no difficulty in separating M. hreviloha from M. poly- 

 morpha. The new species is smaller, it lacks marginal ventral 

 scales, the appendages of the median scales have larger cells 

 and usually fewer marginal teeth, the epidermal cells are more 

 complex being surrounded by more rows of cells, there are no 

 epidermal papillae, the stalk of the male receptacle has air- 

 chambers and usually more rhizoid-f urrows, the disc is more 

 deeply and more unsymmetrically lobed, the stalk of the female 

 receptacle has more rhizoid-furrows, the disc is less deeply lobed, 

 and the lobes are flattened instead of being terete. The difference 

 in the cupules, already noted in connection with M. paleacea, 

 would apply equally well in separating the species from M. poly- 

 morpha. 



6. Marchantia domingensis Lehm. & Lindenb. 



Marchantia domingensis Lehm. & Lindenb. ; Lehmann, Pug. 



Plant. 6 : 22. 1834. 

 Marchantia inflexa Nees & Mont.; Montague, Ann. Sci. Nat. 



Bot. II. 9 : 43. 1838. 

 Marchantia disjuncta SuUiv. Am. Jour. Sci. II. i : 74. 1846. 

 Marchantia linearis G. L. & N. Syn. Hep. 529. 1847 (in part). 



Not Lehm. & Lindenb. 

 Marchantia martinicensis Spreng. ; G. L. N. /. c. 531. 1847 (^s 



synonym). 

 Marchantia Elliottii Steph. Bull. Herb. Boissier 7 : 400. 1899. 

 Marchantia caracensis Steph. /. c. 526. 1899. 



Thallus pale to dark green, not glaucous, slightly or not at 

 all pigmented with purple, usually 4-6 mm. wide and 2-3 cm. 

 long, dichotomous, the successive forks usually 1-1.5 cm. apart, 

 texture delicate, margin entire ; epidermis composed of cells with 



