BRITTON: FLORA OF THE VIRGIN ISLANDS 113 



thicker, and more continuous. Furthermore, the apothecia are more 

 concave, with the persistent thalline margin more conspicuous. 



41. Parmelia cetrata f. suBisiDiosA Muell. Arg. On tree-trunk. 



Crown, 1441 in part. North Carolina, Florida, Cuba, Jamaica. 



42. Parmelia conspersa (Ehrh.) Ach. On rocks. Crown, 450 m. 



altit., 1358. 



43. Parmelia latissima var. cristifera (Taylor) Hue. On tree- 



trunk, St. Peter, 1249; on twig. Crown, 1441 in part. 



44. Parmelia perlata (L.) Ach. On rocks, near Bonne Resolution, 



446; on Spondias, Mandal, 1311. 



45. Ramalina complanata (Sw.) Ach. Without data, 1356a. 



46. Ramalina gracilis (Pers.) Nyl. On twigs of Giiettarda, Crown, 



450 m. altit., 1356. 



47. Blastema nigrocincta Riddle sp. nov. 



Thallus crustaceus arete adnatus sat crassus, ambitu subradiato-laciniatus 

 effiguratusque, centro limoso-aieolatus, areolis 0.4-0.8 mm. latis leviter convexa 

 primum contiguis demum hypothallo nigro dispersis, cincreo-albescens dein fumosus 

 aut partim luridus. Apothecia 0.3-0.5 mm. lata, superficialia dispersa vel partim 

 caespitosa nuda, disto piano vel leviter convexa ferrugineo-aurantiaco, margine 

 proprio sat tenue persistente nigro nitido, margine thallino nuUo; e.xcipulo externe 

 coeruleo-nigro interne incolore; epithecio ferrugineo; hymenio incolore; hypothecio 

 pallide fuscescente. Asci 8-spori. Sporae incolores ellipsoideae biloculares placodio- 

 morphae, loculis poro tenue confluentibus, 12-14 ^ 5^6 /j. 



On rock, Tutu, St. Thomas, collected by Mrs. E. G. Britton and 

 Miss Delia W. Marble, Feb. 8-9, 1913, no. 469a (type!). Also, on 

 limestone, Montalva, Porto Rico, N. L. Britton, J. F. Cowell, and 

 Stewardson Brown, March 2-4, 191 5, no. 4810. 



This species is distinct in the contrasting coloration of the black 

 margin and the orange disk of the apothecia, a character which 

 will serve to distinguish it on the one hand from species with similar 

 thalline characters, such as Bl. Forstroemiana (Fr.) Muell. Arg.; 

 and on the other hand from Bl. ferruginea (Huds.) Koerb., where the 

 disk and margin are concolorous, and from Blastevia peragrata (Fee) 

 Muell. Arg., where the margin is black, but the disk is aeruginous- 

 brown . 



48. Caloplaca diplacia (Ach.) Riddle comb. nov. 

 Lecanora Ach. Synop. Lich. 154. 18 14. 



On rock, near Charlotte Amalia, 493, 495, 1485 in part. Also 

 recorded by Nylander in Flora 63: 127. 1880. Apparently confined 

 to the West Indies. 



49. Caloplaca murdrum (Hoffm.) Th. Fr. On rock, near Charlotte 



Amalia, 1485 in part. 

 9 



