189 
covered with Cyanophyceae, either in the form of olive, green, 
or brownish gelatinous clumps, or as incrustations of the most 
varied shades of blue and black, whilst the practical absence of 
Chlorophyceae is very notic eable. In the Aroid house (No. 1), 
which is also subjected toa moist heat, the north wall especially, 
t 
ms 
are interspersed. One or other of the species of Lyngbya usually 
forms a laminose coating all over the sides of the tanks. 
(ii.) The Thames-/flora, consisting of the Algae in the artificial 
greenhouses Piona Regia tank, the’ ‘an ks of the Vir 
house) show the same constituents, and I have scarcely observed 
nd een 
been dee with plants from Brazi 
The Thames-flora consists of a denm number of inc ME Algae 
and of numerous os (unicellular or few-celled) species, 
amongst which the genera Scenedesmus and Padiastrum are 
particularly common. The Platon of all the TES T Kew in 
its composition absolutely resembles that of the Tham 
(iii.) The terrestrial flora, made up of the tege growing o 
damp ground BM ena Nostoc) and rocks ( Nostoc, Gloeocapsa, &c. 5 
and those growing on trees, &c. (Plewrococeus, Chlorococcum), in 
the open a ie 
The greenhouse flora is dM MS apad developed all the 
year round, whereas the flora outside show; its maximum develop- 
ble 
Desmids and other aie oor are very rare befor e Apri although 
some of the unicellular Protococeoideae are he ere to »* found all 
the year round. 
