INTRODUCTION TO CKYPTOGAMIC BOTANY. 395 



in the Pyrenees. I have pubUshed it as Sphceria parmen- 

 taria, but perhaps it ought rather to be considered a Py- 

 renastrum (= Parmentaria). Indeed, had not Pyrenastrum 

 been a tropical genus, there would, probably, have been no 

 hesitation on the subject. In some of the tropical species 

 the 'perithecia are very highly developed and of considerable 

 size, but they vary greatly in the same individual. Some- 

 times, however, this is deceptive ; for, as they are often spread 

 out at the base, as in V. variolosa (Fig. 82, b), when the 

 cuticle of the plant or the crust wears off entirely, more of 

 the walls are exposed, and they appear, in consequence, much 

 larger than before. The genus Verrucaria is universally 

 diffused, but a very large number of the species are peculiar 

 to the barks of tropical trees, and in such the perithecia attain 

 their greatest size. Tulasne figures curved spermatia like the 

 spores of some Septoria in Verrucaria muralis. 



4. Endocarpei. 



Excipulum pale, single or double, at length piercing the 

 horizontal thallus by a distinct ostiolum. 



433. The species of this group are distinguished by their 

 perithecia being included in the substance of the thaUus, and 

 never carbonised, as in true Verrucarice. The crust is, for 

 the most part, foliaceous, though there are species which de- 

 part from the more typical forms in this respect. The distinct 

 ostiolum and gelatinous nucleus distinguish them from Par- 

 meliacei, with which they agree in some respects. The folia- 

 ceous frond assumes the appearance of Hepaticce or Cyphella, 

 but it is mere analogy without the slightest relation. In En- 

 docarpon (Fig. 82, c), the thallus is, for the most part, peltate. 

 The species grow on moss, exposed earth, and stones, while some 

 are frequently or periodically submerged, and during the 

 greater part of their life, when not actually beneath the water, 

 constantly moist with its spray. The nucleus is, for the most 

 part, coloured, and the frond varies much in hue. In Sagedia 

 the perithecia at length assume a darker tinge, so that we 

 have the habit of Endooarpon, with somewhat of the cha- 

 racter of Verrucaria, though they are never really carbona- 

 ceous. In Pertusaria we have a distinct crust, with the peri- 



