36^ ALGM CONFERVOIDE.E. [Trentepohlia. 



very short heaped together fragile moniliform slightly branched, 

 branches simple subulate spine-like divaricate, articulations 

 rather shorter than broad, joints contracted. 



On Yews, at Cleish Castle, Kinross-shire, Mr. Arnvtt.— (i This singu- 

 lar plant resembles none other that I know. It is found only on Yew- 

 trees : these are of great age, and have, in general, near the root a very ir- 

 regular outline, exhibiting deep cracks or clefts : from these fissures exudes 

 the juice of the tree; this soon afterwards thickens and becomes covered 

 with a soft filamentous substance that might be mistaken for Racodium 

 cdlare or rather R. vulgare, Fries, if indeed it has not been frequently pass- 

 ed over for that plant. Such is its first state. The sap of the tree continues 

 to flow through the plant, which also increases in size and thickness, at 

 last becoming a firm corky almost hemisphaerical substance, losing nearly 

 all trace of the filamentous surface, and slightly resembling specimens 

 of Sphceria deusta; presenting like them, when broken, though generally 

 very indistinctly, the appearance of concentric layers, which, from the 

 observations 1 have made, mark pretty nearly the number of years the 

 specimen has been in forming. This I have no doubt is caused by the 

 inspissation, at the close of each season, of the sap of the tree absorbed 

 by the parasite. I may add, that when well dried, this species takes 

 fire very readily from a spark, and burns like tinder." Am. in lilt. 



81. Trentepohlia. Ag. Trentepohlia. 



Filaments minute, tufted, erect, coloured, articulated; dissepi- 

 ments hyaline. Fruit ; tufted, terminal capsules — Named in 



honour of" a German botanist The species inhabit fresh water 



or marine rocks and caverns. 



1. O. purpurea, Ag. (purple Trentepohlia^); filaments erect 

 very minute forming continuous velvetty patches slightly 

 branched, branches dichotomous, articulations twice as long as 

 broad. — Ag. Syst. Alg. p. 36. — Conferva jmrpurea, Dilhv. Conf. 

 t. 43. — By ssus purpurea, Light/. — E. Bot. t. 192. 



On rocks and stones, near the sea. Icolumbkill, Lighffoot. Angle- 

 sea, Rev. H. Davies. In a cavern at Swansea, Dillw. Abundant in Fin- 

 gal's cave, Stafta, W. H. Harvey — This forms exceedingly thin unde- 

 fined patches, of a dull purple colour, resembling a* mere stain on the 

 surface of the rock. The filaments are scarcely a line high and very 

 sparingly branched. It has many points in common with Calithamnion 

 Rothii, and I am almost inclined to think it may be that species, altered 

 by growing in situations where it is only occasionally wet with salt 

 water. 



2. T. pulchella, Ag. (beautiful Trentejwhlia); filaments virgate 

 tufted much branched, branches erect alternate beset with short 

 opposite or secund ramuli, articulations four times as long as 

 broad, capsules racemose. — Ag. Syst. Alg. p. 37. — Conferva 

 nana, Dillw. Conf. t. 30, (according to authentic specimens). 

 E. But. t. 2585. — j3. chalybea, Ag. — Conf. chalybea, Dillw. Conf. 

 t. 94 C. corymbifera, E. Bot. t. 1666./ 1. 



In mountain-streams ; growing on the naked rock, or on aquatic mosses, 

 &c. — Filaments one-eighth to one-half of an inch long; forming fine 



