MELOSIRA. 



439 



Fig 166. Melosira sulcata. 



Fig. 167. Melosira 

 Roeseana, var. dentroteres. 



Fisr. 168. Melosira arena ri a. 



The species of the genus Melosira are scattered throughout the world. 

 The genus includes a large number of species, which have been divided by 

 various authors into several different genera. Without admitting these genera 

 the Melosira may nevertheless be divided into various groups, viz. : 



Gallionella, the valves of which are carinate ; 



True Melosira without keels, the valves being simply punctate ; 



Paralia, the valves of which are both punctate and areolate. 



We represent here Melosira varians Ag. (fig. 165), Melosira (Ortliosira) 

 arenaria Moore (fig. 168), Melosira (Paralia) sulcata (Ehr.) Kiitz. (fig. 166), and 

 lastly Melosira Boeseana Rabh., of which Ehrenberg made a special genus 

 under the name of Liparogyra (fig. 167). 



