THE MARINE BOTANIST. 67 



by Dr. Harvey : — ^^ As a singular production, 

 which^ to the naked ej^e, more nearly resembles a 

 crustaceous lichen than an alga, but its structure 

 aud fructification prove it to be widely different to 

 any lichen." The Leathesiae have tuber-shaped 

 fronds, fleshy and hollow, in L. tuberiformis, while 

 in L. Berkleyi they are soft and depressed. Often 

 nearly of the colour of the rock on which it grows, 

 this plant may be easily overlooked by the collector 5 

 at present it is only known in the south of Eng- 

 land and west of Ireland. The various species of 

 Elachista, and especially the Myrionema, require to 

 be submitted to the microscope for a proper dis- 

 crimination of the species. M. Lechlancherii, which 

 may be found in autumn on the decaying fronds of 

 Rhodymenia palmata, appears a beautiful kind 

 when viewed through the glass 5 to the naked eye 

 it is only apparent in the form of very small round 

 olive spots on the fronds of R. palmata and Ulva 

 latissima. 



