APPENDIX. 



Family Y. CHOEDAEIACE^. 



LEATHESIA CPJSPA. 



Colour. Olive-brown. 



Substance. Always firm and solid. 



Character of Frond. More or less globose; forming small tubers upon the fronds 

 of other algse. The internal threads which compose it, densely crowded. 

 Tubers running together in irregular patches as their growth proceeds. 



Measurement. Tubers from to \ of an inch in diameter; patches an inch or 

 more. 



Fructification. Ulinute seeds {spovQs) concealed in the substance of the frond. 



Habitat. Cumbrae in the Clyde. Growing on Cliondreas crispus. April, May, and 

 June, 1853. Mr. Eoger Hennedy. 



General observers may always know this plant from Leathesia fuheriformis 

 (fig. 54) by its decidedly solid substance. A touch ascertains this at once. 

 And its tuber-like character sufiiciently distinguishes it from L. BerJceleyi (fig. 

 59). The more advanced student, who is disposed to make durch-sclmitts of 

 the two tuberous forms, will observe that the threads which compose the outer- 

 coat (perijjlLery) of L. tuheriformis are short and straight; whereas those of L. 

 C7'ispa are very distinctly curled, and are rather longer: nor are they as regu- 

 larly and roundly bead-like in the latter as in the former. Very little difference 

 is observable in the spores (which are borne among these outer-coat filaments 

 at the base). For scientific description and figure see Natarcd History JReview, 

 1857, "Proceedings of Societies," p. 201. 



ELACHISTA GKEVILLEI. 



Colour. Olive, tending to brown. 

 Substance. Somewhat rigid. 



Character of Frond. A small tuft (rising from a small tubercle); parasitic on 

 Cladophora rupestris. Threads {filaments) slender; simple; tapering to the 

 base; scarcely to the tips; jointed. 



Measurement. From J inch to f long. 



Fructification. Not ascertained. 



Habitat. Largs: Dr. Greville, July, 1852. Corrighills, Arran: Professor Walker 

 Arnott, the same year. 



This little plant is described as "similar in many respects to Fdacliista 

 fucicola (fig. 61), but smaller, with shorter joints and arising from a much 

 smaller tubercle. Remarkable too for growing on one of the chlorosperm algae, 

 whose fronds it often infests as densely as G. fucicola does those of the Fuci." 

 For scientific description and figure see Natural History Review, 1857, "Pro- 

 ceedings of Societies," p. 201. 



ELACHISTA HATDENI. 



Colour. Olive, tending to dark brown. 

 Substance. Soft. 



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