152 



Botanical Society of Edinburgh, 



self had been disposed to consider it a variety of Hypnum eirrhosum. 

 Mr. Wilson had, however, satisfied him that it could scarcely be so 

 considered. In the absence of fructification, Mr. Wilson preferred 

 to regard it as a variety of Leucodon Lagurus (although there were 

 certainly some differences of character) rather than unnecessarily to 

 multiply species. Dr. Greville was still disposed, on the strength of 

 the great difference in habit, to doubt of its claim to the place assigned 

 to it, and thought it probable that the fructification, when discovered, 

 would remove it altogether from Leucodon. 



The following papers were read : — 



1 . "On the Structure of Diatomacete," by E. W. Dallas, F.R.S.E. 



The author directed attention to the list of species which follows, 

 and which, although imperfect, exhibits great variety in the forms, 

 showing the Medway to be very fertile in these organisms. 



Epithemia Musculus. 

 Campylodiscus cribrosus. 

 Surirella striatula. 



linearis. 



Tryblionella marginata. 



Scutellum. 



punctata. 



gracilis. 



acuminata. 



Cymatopleura elliptica. 

 Triceratium Favus. 



striolatum. 



undulatum. 



Cyclotella Kiitzingiana. 



operculata. 



And three species undetermined. 

 Actinocyclus undulatus. 



senarius. 



septenarius. 



octonarius. 



Nitzschia sigmoidea. 

 dubia. 



ill 



nonarms. 



Eupodiscus Argus, 2 vars. 



radiatus. 



-^ — maculatus. 

 Coscinodiscus radiatus. 



minor. 



eccentricus. 



Thwaitesii. 



And an undetermined species. 

 Cocconeis Pediculus. 

 Scutellum. 



And an undetermined species. 

 Navicula elliptica. 



convexa. 



Westii(?). 



didyma. 



pusilla. 



punctulata. 



palpebrahs. 



Pinnularia divergens. 

 Stauroneis pulchella. 

 Cocconema parvum. 

 Pleurosigma balticum. 



Hippocampus. 



angulatum. 



acuminatum. 



distortum. 



Doryphora Amphiceros, vars. 



Boeckii. 



Achnanthes brevipes. 

 Grammatophora marina (?). 

 Biddulphia aurita. 

 Zygoceros rhombus. 

 Dentricella sp. 

 Orthoseira sp. 

 Dictyocha. 

 Bacteriastrum furcatum (?). 



curvatum (?). 



Some of the species in the foregoing list have been described as 

 new to Britain, by Mr. Roper in a paper recently published in the 

 * Microscopical Journal.' The Coscinodiscvs, not named, seems from 

 the description to be the same with that found at the mouth of the 

 Thames, and is an exceedingly J)eautiful disc. The four species of 



