OF ARTS AND SCIENCES. 403 



the hypotliecium. P. sorediata, var. endochrysa, M. & V. d. Bosch, in 

 Montag. Syll. p. 345, "thalli strato meduUari fulvescente (chamois)," 

 described from specimens of Junghuhn, is an indication of the last- 

 mentioned feature, which appears to me to show itself (though doubt- 

 less finally disappearing, and unknown in a) with moi'e or less distinct- 

 ness, in most of my specimens. In P. coccinea, M. & V. d. Bosch, 

 Lich. Jav. p. 40, the same layer is described as blood-red. As already 

 remarked under our first species, the present differs from that in pos- 

 sessing the pseudo-Lecideine apothecia of the genus, as defined by its 

 illustrious author, and others ; only varying from their descriptions in 

 the fructification, being at first pale (as indicated by the present writer, 

 1. c.) and also, in the variety now before us, bespread at length with a 

 gray bloom (comp. Eschweiler's " apothecia . . vix canescentia " in his 

 Lecidea albo-virens, 1. c), which is very often wanting. The spores of 

 the present foi'm do not differ appreciably from those of other species, 

 unless in proportional dimensions. They are often ellipsoid, slightly 

 constricted at the middle, once-septate, and fuscous ; about two and a 

 half times longer than wide : but occur perhaps more commonly in a 

 rather elongated, oblong, less colored and less simple state, in which 

 the protoplasm develops at first (as in many spores) into a square, or 

 oblong sporoblast, which then divides into two, which are connected by 

 a narrow isthmus (like the neck of an hour-glass, or, more often, of 

 dumb-bells) through the middle of which passes the dissepiment of the 

 spore ; which reaches, in this state, to nearly the length of the spores 

 of P. 3Ieissneri. The ends of the sporoblasts towards the (empty) 

 tips of the spore are so well defined that it is diflicult not to describe 

 these sporoblasts as becoming at length larger, oval, and once-septate, 

 and the spore as thus thrice-septate (and this view has been taken by 

 eminent writers), but I venture to propose the above as perhaps the 

 true one ; and to regard the genus as possessing spores typically once- 

 septate ; and as approaching, therefore, species of Physcia as closely in 

 this respect, as it does also, according to Dr. Nylander (in his observa- 

 tions on P. 3Ieissneri, in Lich. Exot. 1. c, p. 255) in its spermogones. 



Pyxine retirugella, NyL Lich. Exot. 1. c, p. 240, is the only 

 remaining species known, not above noticed. In this, which was col- 

 lected in Nukahwa, growing on stones and rocks, by Mr. Jardin, the 

 thallus is described as reticulate-rugulose, like that of Parmelia saxa- 

 tilis ; and the apothecia as resembling those of the last species. Very 



