AMPHIPRORA. 26l 



(Group) Amphiprora Cleve, 1891. 



The genus Amphiprora was created in 1843 by Ehrenberg in his 

 " Verbreitung und Einfluss, etc.," p. 113, from a form which no one has 

 been able to identify. 



Prof. Pfitzer, in 1871, re-arranged the species which authors had 

 up to that time described, and divided them into his Amphitropis and 

 Phigiotropis. 



Prof. Cleve has lately re-constructed the genus in " Le Diatomiste " 

 (1891), by subdividing the forms into a number of very characteristic 

 groups. 



In his Monograph on the Naviculaceae Mr. Cleve adopts the 

 following classification, which we accordingly accept : 



Analysis of Sub-genera. 



r ,- ,, ( Raphe sigmoid .... 



Girdle view J 



P lc e ' ( Raphe not sigmoid, but bi-arcuate and very eccentric 



f Raphe central .... 



Girdle view 1 . ,- , e , ., , 



r / /Keel 01 both valves running in opposite 



not plicate , R , j di cti ns , 



( Iropidoneis). ' < 



. v ' 'I eccentric J 



l_ ,. \ Keel running in one direction 



Amphiprora. 

 Auricula. 



f Orthotropis. 



i 



i Plagiotropis. 

 ^Ampboropsis. 



GENUS 24. AMPHIPRORA (EHR.) CLEVE, 1891. 



Valve carinate, with keel sigmoid through a more or less sinuous 

 line of suture, united to the lower portion of the valve. Axial 

 hyaline area absent, median area absent or small. Central nodule 

 small. Connecting zone with longitudinal plaits. 



ANALYSIS OF SPECIES. 



f Keel with coarse puncta very slightly produced and very 

 Alas not J distinct, about 4 in i c.d.m. . . . .A. alata. 



undulate. ) 



V. Keel without coarse puncta ; stria; fine . . .A. paludosa. 



,. Aire undulate, festooned . . . . . . .A. ornata. 



