136 



3. Thallus very firm, easily loosened from the sub- 

 stratum, irregular in form ; perithallus with in- 

 ferior part of large cells, superior part with 



smaller cells; colour brick red 



P. polymorpha (Zan.) Schm. 



b. Thallus membranaceous-calcareous with long apical 

 cell as high as hypothallic cells, orbicular with slight 

 radial lines and concentric zones; colour pink or red. 



P. rubra. 



Subgenus 1. Cruoriella Cm. 



1. Peyssonnelia (Cruoriella) armorica (Cm.). 



Cruoriella armorica Crouan in Ann. Sc. Nat., 1859, 4e serie. t. 12; Flor. 

 du Finist. 1867, p. 148, tab. 19, fig. 128. DE TOM, Syll. Alg. vol. IV, 1905, 

 p. 1691. 



This small alga was detected growing on other Peyssonnelia. 

 Thanks to the extreme kindness of M. HARIOT, assistant au Mu- 

 seum d'Histoire Naturelle at Paris, I was able to compare it to 

 an authentic specimen of CROUAN. The comparison showed the 

 absolute identity of the two specimens. 



Found at St. Thomas in the sea to the west of Water Island in a 

 depth of about 15 fathoms. In alcohol. (No. lllOni). 



Geogr. Distrib.: Atlantic coast of Europe, Mediterranean Sea. 



2. Peyssonnelia (Cnioriella) Dubyi Crn. 



CROUAN, Ann. d. Sc. Nat. 1844, p. 368, tab. 11. SCHMITZ, Uebers. der 

 Florideen, 1889. p. 20. DE TONI, Syll. Alg. vol. IV, sect. IV, 1905, p. 1691. 



Peyssonnelia Dubyi belongs to the subgenus Cruoriella because 

 its hypothallus consists of fan-shaped little groups of filaments. 

 These filaments have in horizontal direction a short and in ver- 

 tical direction a high apical cell, higher than the cells in the 

 hypothallic filaments. 



P. Dubyi was the only known Squamariacea of the West- 

 Indian region before Dr. BORGESEN'S Expedition. 



Found at St. Thomas in the sea to the west of Water Island in a 

 depth of 15 fathoms. (N. 1030). Dry specimen. 



Geogr. Distrib.: Atlantic coast of Europe. 



