188 Prof. Forbes's Note in reply to Mr. Hassall. 



all his figures, in which case the filaments of T. pectinata would 

 be almost equal in diameter to those of T. porticalis, and conse- 

 quently nearly as large again as those of the present species. 

 Tyndaridea immersa. Filaments rather smaller than those of the 

 preceding species ; cells usually twice or twice and a half as 

 long as broad ; sporangia usually spherical, but sometimes oval 

 and entu-ely confined to the transverse tubes. Fig. 18. 

 Hab. Wimbledon Common. 



Tyndaridea decussata. Filaments of less diameter than those of 

 the preceding species ; cells usually two and a hah" times as long 

 as broad ; sporangia circular, and a portion of them immersed 

 either in one or other or both cells. See fig. 19. 

 Hab. Wimbledon Common. 

 This species may ])ossibly be the T. decussata of Vaucher, in 



which however the cells are said to be four times as long as broad. 



Tyndaridea Ralfsii. Filaments of less size than those of T. im- 

 mersa ; cells usually fom* times as long as broad ; s})orangia el- 

 liptical, their long diameter corresponding with the length of 

 the cell. Fig. 20. 

 Hab. Penzance, Mr. Ralfs ; near Cross-in-Hand and Chdting- 



ton Common, Mr. Jenner. 



There is not a more elegant or beautiful species than this in 



the genus, and I have much satisfaction in dedicating it to Mr. 



Ralfs, its fii'st founder, and a gentleman by whom om- knowledge 



of the Algse has been so considerably augmented. 



XXVI. — Note in reply to Mr. Hassall. 



By Prof. Edward Forbes, V.P.W.S., F.L.S., F.B.S. &c. 

 I REGRET that Mr. Hassall has taken in such apparent ill-hu- 

 mour my comments on two of his supposed discoveries. His 

 observations, however, more and more convince me that he is 

 mistaken in regard to the Echinocorium, and had not made him- 

 self acquainted with previous observations when he claimed the 

 priority of discoveiy about the phosphorescence of zoophytes. 



A word or two regarding each : I have met with the Coryne 

 on shells not incrustcd by Alcyonidium echinatum as well as those 

 so invested : Mr. Hassall has not hitherto. This is just the state 

 of the case about the association of Adamsia maculata Avith the 

 Pagurus, and of the Adamsia with the remains of Echinocorium, 

 but one negative observation (I have made many) upsets all his 

 positions. 



Mr. Hassall says, that he has convinced himself of the union 

 between the Alcyonidium and Coryne ; first, because marked de- 

 pressions exist on the polypidom for the reception of the bases of 



