CHORDABIAC] -11 



Hah, Atlantic shores of Britain. On rocks and Btonee in the 

 i, about half-tide leyel. Annual. Summer. Common. 

 This species, the besl Known and earliest described of 

 the genus, as qo^i restricted, appears to have been first 

 noticed by Dr. Dnimmond, who discovered it cast onshore 

 a( Lame, in August 1st'.;. It is common on many parts of 

 the coasts of England, Scotland, and Ireland, and is found 

 in the island of Jersey. In the QOrth-east of Ireland, 

 where it was first noticed, Mr. Thompson finds it in pro- 

 fusion, and has observed, among heaps of seaweed cast on 

 shore, "the partiality of the Idotea a 8trum t Leach, for the 

 gelatinous Mesogloia vermicularis t plants of which it had 

 very much eaten. Leaving the other Algae, of which there 

 were many species in the heap, quite untouched." 



54. Griffithsiana (Mrs. Gfriffiths's Mesogloia) ; frond Blender, 

 equal throughoul ; branches alternate or irregular, filiform, 

 long, simple, nearly bare of ramuli, Gfrev. MS. .• Hook. Br. Fl. 

 v. 2. p. 387. (Atlas, PI. XXV Fig. 50.) 



Hob. Atlantic shores of Britain. In rock-pools between tide- 

 marks, rare. Annual. Summer. 

 This species hears a striking resemblance in its ramifi- 

 cation to Chordariaflagelliformis, hut is always of a much 

 paler colour, and the microscopic structure very different ; 

 the axis being much less dense, and the Bubstance more 

 gelatinous and tender. Still there is a considerable simi- 

 larity in structure, and evidently an affinity, through this 

 Bpecies, between the two genera. 



55. virescens (The pale-green Mesogloia) ; frond filiform, gela- 

 tinous ; branches Long, slender, villous ; ramuli numerous, pa- 

 tent, short, linear, obtuse, Carm. : Hook. Br. Fl. v. -. p, 

 (Atlas, PL XIV. Fig. 57.) 



Mesogloia affinis, Berk. M. BEornemanni, Suhr.? Tricholadia 

 virescens, Harv. Helminthocladia virescens, ffarv. Meso- 

 gloia gracilis, Carm, M. Zosteree, Aresch. Rivularia Zos- 

 teraB, Mohr. 

 Hob. Northern -here- of Britain. On rocks, stones, and Algae, 

 at half-tide level. Annual. Spring and summer. Common. 

 An abundanl species on all our coasts, from the oorth 

 of Scotland to ( Jornwall, and subject to little variation ex- 

 cept in the amount of its ramification. Sometimes the 



branches are even more densely set than our figure repre- 

 sents ; often they are more distant, and occasionally the 

 frond is very much less divided. The appearance of a 

 branch of this species under the microscope is verj beau- 



