(18) 



widening, the ultimate ones minute, mere lacinise or teeth, often forming 

 a beautiful fringe of minute ciliee. Tubercles spherical, sessile, scattered 

 along the margins of the frond, and containing a mass of conical spores. 

 Tetraspores cruciate (?), forming patches near the extremities of the 

 upper segments of plants M'hose divisions are naiTower than those 

 bearing tubercles. Structure cellular ; central cells rather large, those at 

 the surface very minute. Substance membranaceous, delicate, adhering 

 to paper in drying. Colour, a bright crimson lake, not changing in 

 drying. 



This beautiful species is extremely rare in this country, and always 

 very stunted in its growth. Its centre of distribution seems to be the 

 fine bays on the western shores of the North Atlantic, where it is 

 frequently found in great abundance and of large size, often three times 

 the size of any found on the shores of Britain. In this country it is 

 quite a northern plant, being mostly confined to the northern shores 

 of Scotland, and the Orkney and Shetland Islands, but everywhere 

 scarce ; still, however, exhibiting as many variations in form and 

 ramification as the more luxuriant specimens from the Western World. 

 At one time narrow, linear, repeatedly divided, the branches subpalmate 

 or alternate, narrowed to the summits ; at another once or twice divided, 

 the segments broad, rounded, almost entire, with the apices multifid or 

 laciniated. 



EXPLANATION OF PLATE LXXIL 



Fig. 1. — Euthora cristata, natural size. 

 2. — Apices of lacinise witli teti-aspores. 

 3. — Tetraspores. 

 4. — Section of a coccidium. 

 5. — Spores. 

 6. — Slice to show internal structure of frond. All mamified. 



