3 1 1 ESCHARID^. 



formed by the elevation of the peristome, is more or less 

 triangular, or (occasionally) almost orbicular. The cell- 

 wall is either punctured round the margin only, the 

 central portion remaining entire, or is thickly covered 

 over the whole extent with circular pores. The median 

 avicularium seems to be constant ; but the large spatulate 

 form is in most cases rarely developed, and always in 

 connexion with the ovicell. 



The differences in the mode of growth are similar to 

 those which we find in Lepralia foliacea and other species. 

 The crustaceous habit seems to be the prevalent one. On 

 the south-western coasts, where S. Landsborovii is abun- 

 dant, I have never met with it in the erect foliaceous 

 state ; but in certain localities it rises into free lamellate 

 fronds, which anastomose and form coral-like masses 

 (woodcut, fig. 15). It assumes both the Escharine and 

 Hemescharine habit ; and under the older system of classi- 

 fication three genera would have about an equal right to 

 claim it. 



These are the chief variations to which the species is 

 liable, apart from the superficial changes dependent on 

 age and locality. 



Lepralia crystallina, Norman, is a small and very 

 delicate variety of the present species, distinguished by 

 its highly developed peristome and produced triangular 

 secondary orifice, and by its bright and hyaline appear- 

 ance. It is a deep-water form. 



The variety porifera, Smitt, is characterized by its 

 short ovate cell with a thickly punctured surface, its 

 slightly developed peristome, and suborbicular secondary 

 orifice, and by the total absence of the central tooth. 

 The ovicell also seems to be smaller than that of the 

 normal S. Landsborovii ; and the spatulate avicularia are, 

 I believe, always wanting. Smitt, in his latest paper 



