274 Evans : Hepaticae of Puerto Rico 



* 



and includes species belonging to the two modern genera Coluro- 

 lejeunca and Leptolejennca. Many years later Trevisan * revived 

 Dumortier's genus Cohtra, giving it the same hmits as the section 

 Ceratanthac of the Synopsis. The subsequent history of Cerato- 

 lejewiea is the same as that of other genera of the Lejeuneae ; it 



was first described as 



t 



t 



Ceratolejainca Is composed entirely of tropical and subtropical 

 species and attains its highest development in the mountainous for- 

 ests of America, A few species, however, are known from paleo- 

 tropic regions and from the islands of the Pacific. The plants 

 usually grow on rotten logs or on the bark of trees or shrubs but 

 sometimes occur on shaded rocks or even on living leaves. As a 

 rule, a given species is more or less particular in its choice of a 

 substratum. In some cases the plants grow mixed with other 

 hepatics but it is much more usual to find them in pure mats, 

 which sometimes measure several feet in length. The stems are 

 at first prostrate and cling closely to the substratum, but in old 

 mats the plants become depressed-cespitose and often stratified 

 in appearance and the branches assume a more or less parallel 

 position. 



Although classed among the Lejeuneae Schizostipae, the spe- 

 cies of Ceratolejennea are more robust than is usual in this group 

 and are further distinguished by their olive-brown color and by 

 their glossiness. The color is due to a pigmentation of the cell- 

 walls and is sometimes pronounced enough to make the plants 

 appear almost black ; under other circumstances it is hardly 

 sufficient to mask the green color of the chloroplasts. In their 

 general appearance the plants bear a strong resemblance to certain 

 genera of the Holostipae, such as Lopliolejeiuiea and Odontolejcnn^^- 



The leaves are imbricated, although rarely densely so, and the 

 lobe is broad and falcate, spreading widely from the axis. In the 

 majority of cases the lobe is convex and the apex more or less 

 reflexed. The antical margin is rounded except in the basal region, 

 but the postical margin is more variable, being sometimes slightly 

 rounded, sometimes nearly straight and sometimes distincUy 



*Metn. r. 1st. Lomb. Ill, 4: 401. 1877. 



t Hep. Amaz. et And. 198. 1884. 



% Engler & Prantl, Nat. Pflanzenfam. i^ : 125. 1893. 



