X ADDENDA ET CORRIGENDA. 



Not uncommon on walls, whether of brick or flint, growing chiefly, 

 but not exclusively, on the mortar. It occurs also occasionally on sand- 

 stone, and on large flints on the downs of Sussex, Mr. Borrer. — " So 

 nearly is this allied to E.fuscellum, that it is now proposed as distinct 

 with considerable hesitation. E.fuscellum is distinguished, however, not 

 only by the thicker, pulvinate, variously tumid, and often deeply fissured 

 thallus, but more essentially by the structure of its apothecia, which 

 are much more minute, and have the brown solid nucleus enveloped, in 

 the immersed portion, only in a thin pellicle of their own colour, and 

 not inclosed in every part in a thick black shell." Borr. 

 Page 207, n. 2, Collema microphyllum, add— E. Bot. Suppl. t. 2721. 



212, n. 25, Collema dermatinum, add— E. Bot. Suppl. t. 2716./. 2. 



221, Roccella tinctoria, add — M. Robiquet has separated the col- 

 ouring matter of this vegetable. The new and singular product 

 which he has obtained has a very sweet flavour, is easily solu- 

 ble in water, colourless, chrystalizes in beautiful flat quadrangu- 

 lar prisms ; — by means of a moderate heat, it may be volatilized 

 without decomposing, and does not acquire the colouring pro- 

 perty till it has undergone successively the action of ammonia 

 and of common air. — Sillimatfs Journal, v. 18. 



246, n. 7, Chara aspera, add— in Wils. E. Bot. Suppl. t. 2738. 



299, n. 3. Gracilaria compressa. To Mrs. Griffiths' name, for the 

 station of this plant, add that of Miss Cutler, from whom I have 

 received most beautiful specimens. 



306, Chcetospora Wigghii. To the station for Sidmouth, add the 

 name of Miss Cutler. 



3-17, n. 29, Calithamnion interruptum, add — Weymouth, Rev. M. 

 J. Berkeley. 



357, after n. 38, Conferva Hutchinsics — insert 



C. rectangular is, Griff. MS. (right-angled Conferva'); filaments thick 

 rigid vaguely branched dark-green entangled, branches distant divari- 

 cate naked below, upper ramuli opposite spreading very short, articu- 

 lations thrice as long as broad. 



Tor-abbey, Mrs. Griffiths and Mr. Borrer. Meadfoot, Mrs. Wyatt. 

 — 2 — 3 inches high, filaments irregularly branched, the branches 

 divaricating and entangled, nearly bare in their lower part, furnished 

 above with short, opposite, one-jointed, spreading ramuli. Articulations 

 2— 3 times longer than broad; joints contracted. Nearly allied to C. 

 Hutchinsics, from which it is easily distinguished by the opposite ramuli 

 and divaricated entangled branches. 



