814 Transactiotis. — Botany. 



C. rostratum, Ehrenberg. (E. XXX.) 



Not common. 



Differs from (7. setaceum in its greater size and in having the slender 

 beaks shorter than the body of the frond. I show the two plants in figs. 

 34 and 35 ; is the distinction between them sufficient ? 



C. acutum, Lyngbye. (E. XXX.) 



Eare. 



14. Spirotsenia, Brebisson. 



S. condensata, Brebisson. (E. XXXIV.) 



Not uncommon in spring. 



This plant is more affected than any other which I have seen by the fluids 

 used for mounting or preserving. I have tried glycerine, camphor water, 

 Ealfs' fluid, etc. ; but they all shrivel up the endochrome considerably, and 

 as the beauty and characters of SpirotcBnia are quite lost unless the endo- 

 chrome be uninjured, preserved specimens are useless. Distilled water 

 even seems to have a bad effect. Almost all other Desmids stand mount- 

 ing in glycerine well, but this is quite spoilt by it. 



15. Ankistrodesmus, Corda. 



A.falcatus,Coix\si. (E. XXXIV.) 



Very common. 



A. acutissimiis, Archer, (Qu. Journ., 1862). 



Eare. 



I had sometimes observed this plant and was struck by its peculiarities 

 before meeting with Mr. Archer's description,* and had considered it a 

 Closterium, but it evidently shows the oblique transverse band, and medio- 

 lateral (to coin a word) pale space referred to by Mr. Archer. The plant is 

 very rare, and from its minute size (g^^ inch long, x^^^^j inch broad) re- 

 quires a high power to examine it. 



Ankistrodesmus sp. indet. 



Figs. 17, 18. 

 Common. 



I have frequently found specimens clearly belonging to this genus, but 

 am doubtful as to its specific affinities. The cells are aggregated in bundles, 

 but instead of crossing each other as in A.falcatus, they are arranged in 

 parallel lines, and they are also only very slightly lunate, often quite 

 straight. In some specimens I observed a definite mucous envelope enclos- 

 ing four such parallel bundles as in fig. 17. 



Length of the cells, -j^^-^ inch ; breadth, ywo's ij^ch. 



Ankistrodesmus sp. indet. 



Figs. 19, 20. 



* " Quart. Journ. of Micr. Science," Vol. 11., New Ser., 1862. 



