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. 
aldtt: 50358: 
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 Guettarda, Crown, 
450 m. altit., 1356. 
47. Blastenia nigrocincta Riddle sp. nov. 
Thallus crustaceus arcte adnatus sat crassus, ambitu subradiato-laciniatus 
effiguratusque, centro rimoso-areolatus, 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 plano vel leviter convexa ferrugineo-aurantiaco, margine 
proprio sat tenue persistente nigro nitido, margine thallino nullo; excipulo 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 x 5-6 yu. 
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 (Fée) 
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, 1485 in part. 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. 
