BRITTON: FLORA OF THE VIRGIN ISLANDS 109 



D. W. Marble 76; hills north of Charlotte Amalia, 4og; on the ground, 

 Magin's Bay to Mafolie, 1312. 



21. Anthoceros punctatus L. 



St. Thomas: in a mud hole, Crown, 450 m. alt., 1363. 



REPORT ON THE LICHENS OF ST. THOMAS AND 



ST. JAN16 



The following report is based primarily upon a study of 90 numbers 

 of lichens from St. Thomas and St. Jan Islands; from St. Thomas, 

 82 numbers collected by Dr. N. L. Britton, Mrs. E. G. Britton, and 

 Miss Delia W. Marble, unless otherwise stated; from St. John, 8 

 numbers collected by Dr. N. L. Britton and Dr. J. A. Shafer. To 

 these have been added a few species recorded by Nylander in Flora 

 (63: 127. 1880) and two endemic species described by Mueller- 

 Argau. Altogether, we have represented 30 genera with 69 species 

 and varieties, of which three species and one variety are here de- 

 scribed as new. The discussion of the characteristics of the lichen- 

 fiora will be confined to that of St. Thomas. 



There is no peculiar element in the lichen-flora of St. Thomas 

 comparable with the gelatinous rock-lichens of Mona Island (see 

 Annals Missouri Bot. Card. 2: 35. 191 5), or with the crustose and 

 gelatinous rock-lichens of Bermuda (see Bull. Torrey Bot. Club 43: 

 146-155. 1916). Such rock-lichens as occur on St. Thomas belong 

 to widely distributed groups even where the actual species are more 

 restricted in distribution. In fact the greater part of the lichen- 

 flora is made up of species more or less common throughout the West 

 Indies or even in the tropics of both hemispheres. It is probably safe 

 to say that there are not more than half a dozen endemic species in 

 St. Thomas. Of the three new species described in this paper, two 

 occur elsewhere in the West Indies. The flora is comparatively rich 

 in the variety of crustose bark-lichens, especially in the genera An- 

 thracothecium with 5 species, Arthonia with 8 species, and Opegrapha 

 with 5 species. It is rather surprising that only one Graphis and no 

 Trypetheliiim should have been collected. On the whole the lichen- 

 flora is rather commonplace. In the following list, stations outside 

 of the Virgin Islands are noted for species, the range of which is 

 limited or not well known. 



LICHENS OF ST. THOMAS 



I. Dermatocarpon hepaticum (Ach.) Th. Fr. On soil, without 

 definite locality, 151. 



'^ Contributed by Lincoln W. Riddle, Wellesley College. 



