NO. 3 dodge: lichens 37 



? Leptogium marginellum (Sw.) S. F. Gray, Nat. Arrang. Brit. 

 PI. 1:401. 1821. 



Santa Maria (Charles or Floreana) Island, Galapagos Islands, W. 

 R. Taylor No. 865. 



A few fragments with tiny coralloid immature apothecia suggest 

 this species. 



Stictaceae 

 Pseudocyphellaria xantholoma (Del.) Dodge, n. comb. 



Sticta Mougeotiana var. xantholoma Del., Hist. Lich. Gen. Sticta 

 63-65, pi t, /. 14. 1822. 



Type: not stated, specimens from Reunion (lie Bourbon) and 

 Mauritius (lie de France), Bory de St. Vincent and Cayenne, French 

 Guiana, mentioned. The following description is based on Costa 

 Rican material as it is more fully developed. 



Thallus 4 cm. high, irregularly pinnately lobed, ultimate divisions 

 more or less dichotomous and truncate, sinuses deep and rounded but 

 not excised, margins elevated, slightly sorediate, shining rugose or 

 slightly scrobiculate, Brussels brown to bister, glaucescent toward 

 the base; below densely rhizinose, clove brown or darker with abun- 

 dant minute yellow pseudocyphellae. Upper cortex 60-70 ju,, appar- 

 ently the highly gelified remains of a tomentogenous layer, dark 

 brown; the rest a pseudoparenchyma of hyaline cells with highly geli- 

 fied walls, the protoplast nearly spherical, 2-3 jx in diameter; the 

 algal layer about 30 p. thick, of compact colonies of Nostoc up to 20 /x 

 in diameter; the medulla variable in thickness, 60-100 /a, of compact 

 periclinal hyphae about 4-5 jx in diameter, thickwalled; lower cortex 

 about 30 /x, consisting of an inner zone of thickwalled brown periclinal 

 hyphae about 10 /x thick, a hyaline zone of very gelified pseudoparen- 

 chyma with very small protoplasts, and an outer tomentogenous 

 zone about 10 fx thick which gives rise to a very dense branched mass 

 of rhizinae, uniformly distributed not in tufts as other species. 



As I have been unable to see the types, I am not sure of the iden- 

 tity of this species although the material fits Delise's description and 

 figures. It is the species commonly but erroneously referred to 

 Sticta Mougeotiana and S. aurigera, also described by Delise from 

 Reunion, Mauritius, and Madagascar. 



Costa Rica: San Jose; Quebradillas, 7 km. n. of Santa Maria de 

 Dota; Standley 429^0; ? Cartago; Pejivalle, 900 m., Standley and J. 

 Valerio (fragments unnumbered). 



