454 Proceedings of the Royal Irish Academy. 



Order X. — CnoBDAELiCE-i;. 

 Spermatochnus, Kiitz. 



S. paradoxus^ Bke. {Stilophora Lynglyei, J. Ag., in Phyc. Brit., 

 pi. ccxxxvii.) 10. 11 H. 12 T. 14 N. 



Grows on Zostera, Cystoseira, and Fiicus. Its branch axils 

 are rounded ; tlie sori are irregular and projecting. Unilocular 

 sporangia are known. 



Stilopliora, J. Ag. 



S. rhizodes, J. Ag. 



On all the coasts, except those of counties "Wicklow and 

 "Wexford. The sori are closer than those of the preceding 

 species. Both unilocular and plurHocular sporangia are 

 known. 



Chordaria, C. Ag. 



Ch. divaricata, C. Ag. 12 T. + Mo. 

 Ch. flayelliformis, C. Ag. 

 On all the coasts. 

 /. /om«, Kjellm. 12 N. 



Mpsogloea, C. Ag. 



This genus differs from Castagnea mainly in the possession 

 of unilocular sporangia, Castagnea possessing both unilocular 

 and plurilocular sporangia. 



M. ve7"miculata, Le Jol. 



This species has been collected on all the coasts except the 

 south, and seems to have been overlooked there, as it occurs on 

 the French and Spanish coasts. 



Castagnea, Derb. et Sol. 



The medulla is solid or hollow. The plurilocular sporangia 

 are formed from the upper joints of the peripheral filaments. 

 In Mesogloea the medulla is solid and loose. 

 C. virescens, Thur. 10-14. 

 C. ZostercB, Thur. 11 He. + ^^. 14 JS". 

 C. GriffithsianaJ. K.g. 10. 11 Mc. 13 N. 



Yery like Chordaria flagelUformis in general growth, but 

 differing in structure. Plurilocular sporangia are unknown. 



