42 



ON THE COLLEMEI OF THE CIRENCESTEE OR 

 COTTESWOLD DISTRICT. 



By W. Joshua. 



It may not be uninteresting to your readers to record what has 

 been done in this very interesting section of Lichenology in the, 

 till recently, unexplored Cotteswold district in the West of England. 



By way of introduction, it may be desirable to state the meteorolo- 

 gical influences which tend to call these fragile plants into existence, 

 and keep them supplied with the necessary nutriment. 



The district under notice is situated on the Great Oolitic forma- 

 tion, near one of the sources of the river Thames, about the centre 

 of the Cotteswold range ; consisting of a long tract of high ground 

 in the eastern part of Gloucestershire, extending from the hills of 

 Stinchcombe and Nibley in the south, to Bredon in the north, and 

 attaining an altitude of from 500 to 1000 feet. 



The soil is various, consisting of open stone-brash, loam, and 

 Bradford and Forest mai'ble clay, alumiue and lime predominating, 

 with 20 to 30 per cent, of siliceous sand. The air is decidedly 

 sharp, but the temperature not unequal. Tlie average annual rain- 

 fall does not exceed 29 inches, which is below that of many other 

 counties. 



The porous nature of the Oolite affords a firm resting-i^lace for 

 the larger Collemei, which flourish principally on the stone walls so 

 common in the district ; here they have the advantage of catching 

 every falling drop of moisture to stimulate their growth, while the 

 smaller forms choose the fresh mortar of the surface, or the sides 

 of damp shady banks, in lanes not wholly obscured from the sim. 

 It is a curious fact that, although containing in a moist growing 

 state, as has been lately ascertained by Professor Church, from 75 

 to 95 per cent, of water in their composition, they resist, equally 

 with other lichens, the greatest extremes of heat and cold. 



The Collema nigrescens, L., I believe to be the only representa- 

 tive of the Corticolons species, but I have recently discovered on 

 leaves of the Portugal laurel, associated with Strigula Babingtonii, 

 Berk., a collemoid growth. The C. e2n2)Jii/llvm of Leight., which 

 has proved to be Atichia Mosigii, Flot., the true place of which, in 

 the entire absence of all fructification, is somewhat uncertain. The 

 species belonging to this tribe, which^ have come under my own 

 notice in the district, are as follow : — 



Collemopsis Sctsereri, Mass. Abundant in old quarries. Cowcombe Wood,near 



Chalford 

 ,, Arnoldiana, Hepp. A new British addition, but scarcely differing 

 from C. Flotoviana. On the Oolite in the 

 former locality. 

 Collema myriococcum, Ach. On walls ; not very common. Barnsley Park, 



near Cirencester. 

 C, auriculatum, Hffm. ") Different conditions of the same species, and 



farvum, Ach. ( occur abundantly on walls, frequently well 



dormatinum. C fruited throughout the district. 



tunaeforme. J 



