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, 131 1. 



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



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



450 m. altit., 1356. 



47. Blastema nigrocincta Riddle sp. nov. 



Thallus crustaceus arete adnatus sat crassus, ambitu subradiato-laciniatus 

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

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

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

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

 proprio sat tenue persistente nigro nitido, margine thallino nullo; excipulo externe 

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

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

 morphae, loculis poro tenue con'fluentibus, 12-14 x 5~6 m- 



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, 1915, 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 Blastenia 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. 1814. 



On rock, near Charlotte Amalia, 493, 495, 14^5 m P art - Also 

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

 to the West Indies. 



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

 Amalia, 1485 in part. 



9 



