144 



has no more than five or six layers of cells and thalli with three 

 layers of cells carried even nemathecia with tetraspores. A spe- 

 cimen (No. 1110 11 ) preserved in alcohol, carried nemathecia with 

 tripartite, zonate carpospores (Fig. 148); one layer of cells under 

 the nemathecia was exceptionally high in another plant. Some 

 plants have a thick basal layer of mucuous substance, but this 

 character is not constant. 



To sum up the differences between P. simulans and conchi- 

 cola we find that P. simulans has a lighter colour, does not ad- 

 here to the substratum and that it must carry more carbonate 



of lime in its tissue for, 

 after decalcification, the 

 cells loosen easily from 

 each other in vertical 

 direction. The contents 

 of the older cells, con- 

 sisting principally of 

 grains of starch in P. 

 simulans are more ho- 

 mogenous in P. conchi- 

 cola. For all these rea- 

 sons I am, I believe, 

 authorized to describe 

 the present alga as a 

 new species. 





Fig. 148. Peyssonnelia simulans nov. spec. 

 Cross section through thallus with nemathe- 

 cium with carpospores. b. basal layer of 

 mucuous substance. (000 : 1). " 



This species was found 

 at St. Thomas in the sea 

 ^^^^^^ to the west of Water Island 

 in a depth of about 15 fa- 

 thoms (No. HIGH), St. Jan off St. Cruz Bay in depths of .about 10-15 

 fathoms (No. 1916, 1752, 1828), off Ram's Head at depth of about 25 fa- 

 t horns (No. 1943). In alcohol and dry specimens. 



6. Peyssonnelia (Eupeyssonnelia) conchicola Pice, et Grun.(?) 



PICCONE et GRUNOW in PICCONE, Algae eritrea, 1884, p. 317. DE TONI, 

 Syll. Alg., vol. IV, sect. IV. 1900, p. 1700. 



The alga3 from the West- Indies that I call P. conchicola, ad- 

 here firmlv to the substratum and resemble in anatomical char- 



f 



acter the type specimen from the Red Sea. The West Indian 

 ones carry nemathecia with tetraspores, nemathecia with carpo- 

 spores I have never seen. P. conchicola has been described by 

 GRUNOW and PICCONE after barren specimens; it may therefore 



