[Vol. 2 

 36 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



0. polyglossa Nyl., collected from limestone rocks in Cuba by Charles 

 Wright, and not otherwise known, is apparently common on Mona 

 Island, as it is represented by two numbers, each with several well- 

 developed specimens. There occur also 0. lingulata Tuck., previ- 

 ously known from Cuba and Bermuda; a sterile omphalaria related 

 to 0. Wrightii Tuck., but apparently not identical; and one other 

 species of the genus, probably new. It has not yet been possible to 

 identify the species of Collema, and that may also prove to be new. 

 Curiously enough, none of these calciphile species has yet been de- 

 tected among the material collected in Porto Rico. 



"In marked contrast to the rock-lichens, the bark-inhabiting lich- 

 ens are all common species, widely distributed in Tropical America. 

 The genus Trypethelium is best represented, with the species T. 

 Eluteriae (four numbers), T. ochroleucum, and its variety pallescens, 

 and T. mastoideum (two numbers) . There are also such character- 

 istic species as Graphis Afzelii, Melanotheca cruenta, Pyxine picta, 

 Physcia alba and P. speciosa, Parmelia sulphurata and P. tinctorum, 

 and Ramalina complanata and R. Montagnei. Probably owing to 

 the comparatively unfavorable conditions on Mona Island, the foliose 

 and fruticose lichens are mostly small specimens, not well-developed." 



The total flora of flowering plants, as indicated by the col- 

 lection made by Professor Stevens and our own, includes about 

 230 species ; some of them are found only in cultivated grounds 

 on the coastal plain and have probably been introduced by 

 man. The total flora of land cryptogams is probably as great 

 or greater than that of flowering plants, so we may conclude 

 that the land flora of Mona consists of as high as 500 species. 

 So far as the investigation of the collections has proceeded, 

 the only apparent endemic species are a Chamaesyce, which 

 Dr. C. F. Millspaugh has described as new, a Tabebuia, the 

 description of which is herewith included, and two very inter- 

 esting riccias, here described by Dr. Marshall A. Howe. One 

 or more of the lichens may be undescribed. Further explora- 

 tion in Porto Rico and in Hispaniola may very well reveal 

 their presence on these larger islands. It is interesting to 

 have ascertained that the flora of this isolated limestone 

 island is not more highly specialized. It is not necessary, in 

 my opinion, to assume a former land connection between 

 Mona and either Porto Rico or Santo Domingo, because all 

 its native species may readily have reached it through natural 

 agencies. 



