168 Evans : Hepaticae of Puerto Rico 



rounded or very obtuse at the apex. The bracteoles extend the 

 whole length of the spike and are much like the underleaves. 



Several genera of the Lejeimeae Holostipae are more or less 

 closely allied to Archilejeunea. Certain species of Brachiolejeunea 

 and Ptychocoleus, for example, develop a five-keeled perianth which 

 is built up on a very similar plan. In Brachiolejeanea y however, 

 the lobule is differently constructed and shows a larger number of 

 marginal teeth, while in Ptychocolens no subfloral innovations are 



i 



» 



present. Both of these genera, moreover, are composed of pros- 

 trate species which show no distinction between caudex and 

 secondary stems, and which are further characterized by the smooth 

 and wingless keels of their perianths. In Mastigolejeunea the dis- 

 tinction between caudex and secondary stems is well marked but 

 the perianth is sharply trigonous with smooth keels. Spruce 

 divided his subgenus Arc hi- Lejeunea into two sections : Monotro- 

 pella, in which the keels of the perianth are rough and the sub- 

 floral innovations usually occur singly ; and Dibrachiella, in which 

 the keels are smooth and the innovations are sometimes borne in 

 pairs. Schiffner accepts both of these sections, making them sub- 

 genera of his genus Archilejeunea. Whether the slight differences 

 just noted will ever be deemed sufficient to separate the groups 

 generically is doubtful, since they share so many characters in 



common. 



Did/ 



an especially close relationship to Brachiolejeunea and Ptycho- 



colens. 



In its restricted sense Archilejeunea is almost exclusively trop- 

 ical in its distribution. A number of species have been described 

 from Africa and from the islands of the Pacific, but the highest 

 development of the genus is attained in South America, where 

 about half of the known representatives have been collected. At 

 the present time no species are definitely known from Asia and 

 only two species, both belonging to the subgenus Dib/ 



(M 



West Indies. One of these is A. 



other is A. Cruegeri (Lindenb.) Schiffn., originally described from 

 Trinidad. The distribution of these two species beyond the islands 

 where they were first discovered is still imperfectly known. 

 Stephani, to be sure, has reported A. Auberiana from Paramaribo 



