squamarijE. 153 



of the upper vertically elongated, also arranged in fibres at 

 right angles to those of the lower stratum. Pructification 

 lodged in depressed warts, which are irregularly scattered 

 over the surface of the frond: — 1, roundish spores, in 

 necklace-like strings ; 2, oblong, cruciate tetraspores. — 

 Petssonelia, in honour of J. A. Peyssonel. 



Peyssonelia Dubyi. Duby's Peyssonelia. 



Frond membranaceous, from half an inch to an inch in dia- 

 meter ; when young, round ; in age becoming irregularly- 

 shaped, with a waved margin; the upper surface finely 

 striate, the lines radiating from the centre to the edge of 

 the frond. FructificatioA in spongy warts, scattered over 

 the frond. 



This is a species which may easily escape the eye of a 

 collector. It forms a thin^ reddish skin on the surface 

 of rocks or shells, and can only be separated from them 

 with difficulty. Sometimes a portion only of the frond 

 is attached, the ends being left free. 



Genus LIX. HILDENBRANDTIA. 



Frond spreading, in a leathery skin, over rocks and stones, 

 its substance formed of closely-packed, vertical fibres. Spores 

 in warts on the surface of the frond; tetraspores oblong, 

 zonate, minute, simk in the frond. 



Hildenbrandtia rubra. The red Hildenbrandtia. 



Frond at first circular, but becoming irregularly lobed with 

 age, varying in colour from blood-red to dark brown. 



This is an obscure plant, which, although of frequent 

 occurrence, is but little known. To the casual observer 

 it appears to be but a dark stain on the rock on which 

 it grows, and to which it adheres so closely that it is 



