LICHEN. 



Li-hea. 

 Afhwiin 



imple texture. Tfialltit crustaeeous, membranaceous, 



rough, or granulated, uniform. 



The generic name implies a similarity to written cha- 

 racters. There are two sections: Ht/slerina, having 

 oval or elliptical apothecia ; and Alymrina, having them 

 of a linear shape. The former may be illustrated by a 

 reference to the Lichen simplex of the Rev. Hugh Da- 

 vie*, in ten. Trant. vol. ii. Of the latter, a new spe- 

 cie*, named O. trideus, has been observed by Mr. Tur- 

 ner of Yarmouth. 



B. HETEROGENEI. 



9- GRAPHIS. Apothecia linear, immersed, or surround- 

 ed by a spurious border of the thallus ; the perithe- 

 cium forming an interior bonier, within which a na- 

 ked disk is seen, being the upper part of an elonga- 

 ted nucleus, which is cellularly striated within. 

 Thallus crustaceous, menibranaceous, or rough and 

 granulated ; uniform. 



The species of this genus have perhaps a still more 

 striking resemblance to written characters. One of 

 them is the Lichen scriptus of Linnaeus, which is com- 

 mon on the smooth, bark of many of our trees, particu- 

 larly oaks, elms, and birches. A variety of this species 

 is remarkable for having the apotkecia so arranged, as 

 to represent not unaptly many letters of the Hebrew 

 alphabet. 



10. BIATORA. Apothrria circular, immersed, present- 

 ing a concave naked disk, encircled by the perithe- 

 ciuin, which forms a margin ; nucleus compressed, 

 of nearly uniform texture within, and very slightly 

 marked with cellular divisions. Thallus crustaceous, 

 uniform. 



Of tlii* genus there i* only a single species hitherto 

 known, B. turgida, which inhabits rocks in the ele- 

 vated woods of Switzerland. It has much the habit 

 of a Lecidea ; but is distinguished by possessing a pe- 

 rithecium and nucleus. The name is derived from the 

 Greek word /lrr*(, signifying a small jug or bowl. 



. 11. VIRRCCARIA. Apothecia subglobular, partly immer- 

 * *ed in the thallus ; covered by a double penthecium, 

 the exterior one cartilaginous (black, J set with pa- 

 pill. r, which at maturity exhibit small perforations ; 

 nucleus subglobular, cellular, the cells including ve- 

 sicle* of a concatenated form. Tlmllta crustaceous, 

 membranaceous, somewhat granulated or powdery ; 

 uniform. 



Nearly fifty species of Vemicaria are described by 

 Acharius. They are divided into five sections, distin- 

 guished by the nature of the thallus: 1. Lejophloea, 

 with the thallus cartilaginous and smooth ; 2. Blenno- 

 riua, subgelatinous ; 3. IMoicea, crustaceous ; 4. Co- 

 *iztra, crustaceous and powdery ; and, 5. Inoderma, 

 with the thallus somewhat Rponge-like. Few of the 

 spcci<s which fall under this genus have been described 

 by British authors. Two, however, may be mentioned, 

 Lichen teaselatus of Eng. But. t. 533, and L. fuscellus 

 rf Turner, in Uu. Trant. vii. p. 90. Of the 5th sec- 

 tion, it may be added, Sphreria byssacea of Withering, 

 afford* an example. 



IS. ENDOCABPON. Apoihecia globular, included in the 

 _, each covered with a membranaceous, diapha- 

 , simple perithecium, with a small (blackish) 

 perforation, marked by an indistinct border, and pro- 

 jecting from the surface of the thallus ; nucleus glo- 



733 



Lichen. 



Acharian 

 genera. 



bular, commonly furnished with cells. Thallus either 

 crustaceous and uniform, or somewhat cartilaginous, 

 leaf-like, and lobed. 



Among the foliaceous species of Endocarpon, may 

 be mentioned, Lichen miniatus, (E. miniatum, Ach.) L. 

 arnphibius, (E. complicatum, Ach.), and L. aquaticus, 

 (E. VVeberi, Ach.) of English authors. 



13. _TRYPETHELIUM. Apothecium hemispherical, ses- Trypethe- 

 sile, (coloured), including several thalami, or smaller Iium - 

 apothecia ; covered with a thick (black) perithecium, 

 terminating above in a small prominent perforation ; 



the apothecium including the others within its pro- 

 per substance, which is distinct from that of the thal- 

 lus ; the nuclei globular, and furnished with cells. 

 TAatttMinembranaceous, and somewhat cartilaginous ; 

 uniform. 



Only two species of Trypethelium have been descri- 

 bed ; one found on American, and the other on African 

 trees. The common apothecium of this genus, produ- 

 cing subsidiary apothecia, is evidently a distinct organ, 

 and should be distinguished by an appropriate name. 

 In the next two genera, taken from a recent paper of 

 Acharius, it is called Verruca. 



14. GLYPHIS. Apothecia subcartilaginous ; roundish, 

 or somewhat elongated ; naked above, flattish, chan- 

 nelled ; homogeneous within ; many crowded with- 

 in a single wart-like organ, (Verruca,) formed of a 

 coloured substance (black), proper to itself, or distinct 

 from the thallus. Thallus crustaceo-cartilaginous, 

 flatly expanded, and adhering closely ; uniform. 



This genus has been proposed by Acharius, since the 

 publication of the Lichenographia Universalis, in a com- 

 munication to the Linnean Society, which is printed in 

 the 12th volume of their Transactions. It is allied to 

 Trypethelium, in having a peculiar wart-like recepta- 

 cle or verruca, containing several apothecia ; or in hav- 

 ing a common apothecium including several partial apo- 

 thecia ; but it i.s distinguished from that genus by the 

 absence of perithecium, porous opening, and nucleus. 

 The species of Glyphis are found chiefly on the bark of 

 tropical trees. 



15. CHIODECTON. Many apothecia crowded within a Chiodecton, 

 single convex or spherical wart-like organ, (verruca,) 

 formed of a peculiar substance, distinct from the 

 thallus, (white) ; the apothecia somewhat powdery, 

 roundish, (black,) heaped together within the body 



of the verruca, while on its surface appear elevated 

 dots. Thallus crustaceo-cartilaginous, flat, adhering 

 closely, uniform. 



This genus, which is nearly allied to the former, has 

 also been constituted by Acharius since the publication 

 of the Lichenographia, and communicated through the 

 medium of the Linnean Transactions. Only two spe- 

 cies have been described : both are found on American 

 trees ; one on the bark of a remarkable tree, Bonplan- 

 dia trifoliata, better known perhaps by the name of An- 

 gustura. 



CLASS II. COENOTHALAMI. 

 A. PHYMATOIDEI. 



16. PORINA. Apothecia wart-like, formed of the sub- Porina. 

 stance of the thallus, including many thalami, or 



