PERTUSARIACEAE. 477 



variously divided, but with much smoother lobes and larger apothecia than 

 in any other species of this family. Two forms are found : one with 

 abundant apothecia and few lobules, the other sparingly fruited and with 

 the lobes more or less fringed with lobules. 



Family 7. PERTUSARIACEAE. 



Pertusaria muUipuncta (Turn.) Kyi. belongs to the section of the 

 genus in which the apothecia are replaced by soralia (i. e. powdeiy pus- 

 tules). As it is the only species of this section known from Bermuda it 

 will be easily recognized. The only species with which it could possibly 

 be confused is Pyxine picta, but that has a foliose thallus, while all species 

 of Pertusaria have a crustose thallus. 



In the other section of the genus, the apothecia are enclosed in 

 thalline "warts" (verrucae) and resemble the closed perithecia of Pyre- 

 nocarpic lichens. Of these species, Pertusaria tuberculifera Kyi., with a 

 white thallus, has the largest and finest verrucae, measuring two or three 

 millimeters in diameter. In the other three species, the verrucae arc 

 smaller, rarely t over one millimeter, and flatter. P. lutescens (Eschw.) 

 Krplh. has a yellowish-green coloration to the thallus. In P. leioplu< 

 (Ach.) Schaer. and P. pustulata (Ach.) Kyi., the thallus is white to gray 

 or brownish ; in the former the verrucae are generally constricted at the 

 base and the ostioles are scattered; in the latter the verrucae spread out, 

 gradually merging into the thallus and the ostioles are confluent and 

 sometimes appear single. 



Pertusaria tuberculifera and P. lutescens are tropical lichens; the 

 others are widely distributed. All grow on bark. 



Family 8. LECANORACEAE. 



This family is characterized by a crustose thallus and discoid apothecia 

 furnished with a margin colored like the thallus and usually contrasting 

 with the disk. 



Hacmatomma punice.um (Ach.) Wainio will be easily distinguished 

 from all other Bermuda lichens by the bright red disk of the apothecia, 

 set on a gray thallus. It is a common tropical species, growing on bark. 



Five rather closely related species of Lecanora have been found in 

 Bermuda, on bark or old fences. L. pallida (Schreb.) Schaer. is the 

 easiest of recognition on account of the dense white "bloom" covering the 

 flesh-colored disk of the fruit. The other four species, all lacking this 

 bloom, are more difficult to distinguish, as their separation depends mainly 

 upon the color of the apothecia and this is a variable character. Plants 

 with a greenish disk may be assigned to L. varia (Hoffm.) Ach.; with 

 the disk blackening to L. bermudensis Kyi. ; those with the disk decidedly 

 brown, to L. subfusca (L.) Ach.; while those with the disk more or less 

 flesh-colored or pallid belong to L. cinereocarnea (Eschw.) Wainio. The 

 last named is the most abundant of the species of this genus; it varies 

 much in the character of the thallus, from a thick, wrinkled thallus to a 

 form in which the thallus is entirely absent. 



Family 9. PARMELIACEAE. 



The genus Parmelia, with foliose thallus, requires for its development 

 more favorable conditions than occur in Bermuda. Consequently, it is 



