DONKINy ON DIATOMACEiE. 13 



Druridgia,* nov. gen.^ Donkin. 



Filament free, compressed, of two (or few?) frustules; 

 frustules oblong or elliptical, geminate by the persistence 

 of the connecting membrane; valve compressed, elliptical, 

 punctate, siliceous throughout. 



This new genus I have established to refer to it a species 

 whose characters cannot be reconciled either to the genus 

 Podosira, in which the filament is attached, the frustule 

 spherical or cylindrical, and the valve hemispherical, with 

 an absence of silex from its apex ; or to Melosira, in which the 

 filament is composed of numerous cylindrical frustules, with 

 hemispherical valves. ( ^')^., ■ f:-^ 



•14. Dru7'idgia geminata, n.^sp. — Filament of two frustules ; 

 cingulum transparent, delicate ; frustule on F. V. oblong, 

 with rounded angles, approaching to elliptical, brown when 

 dry ; hoop absent, or restricted to a mere line ; valve com- 

 pressed, on S. V. elliptical, minutelv and obscurelv punctate. 

 Length, from -0007" to OOIG"; breadth, '0004". 



In the living state the endochrome presents a large, dark, 

 circular spot at each angle of the filament. 



In the previous number of this Journal Mr. West has 

 described and figured (vol. viii, PI. VII, fig. 11) a form, 

 under the name of Podosira ? compressa, which seems, from 

 his description, to be identical with Druridgia gemi- 

 nata; if so, Mr. West has represented the puncta to be 

 much coarser and more scattered and distinct than they 

 ought to be. So much so, that I feel assured that specimens 

 could not be identified by his figure. Mr. West states that 

 his P. compressa and Atheya decora were found in Druridge 

 Bay and at Cresswell by Mr. Athey, of West Cramlington, 

 from whom he derived his materials. Concerning the publi- 

 cation of these two forms by Mr. West, I think it just to 

 observe that he was well aware, from a call he made me in 

 December, 1859, that I had in my possession a large number 

 of new MSS. species, discovered by me at Cresswell and 

 other localities on the Northumbrian shore, all of which 

 I intended shortly to pviblish, and only a few of which I had 

 time to show to him on that occasion. Now, bearing 

 this fact in remembrance, I hold that Mr. West, before 

 publishing the two species in question, ought to have 

 inquired whether they were amongst the number of 

 MSS. species. If he had done so, I would have in- 

 formed him that I discovered them both at Cresswell, 



* From Druridge, Nortliumberland. 



