QVJlt/^^ 



v^ \ CD) 



LIB 



TROPIDONEIS. 



CV/ 



26 



V 



20 to 22 in 1 c.d.m. Connecting zone with numerous (8 to 10) well-marked 

 plaits. Length, 4^5 to 8 c.d.m. 



Fresh water. This beautiful and rare species has onlv been found once in Belgium, and that 

 in scanty numbers, in a single gathering at Antwerp,' by Rev. P. Gautier. France (Temp. 

 Perag., No. 258), Not yet found in the British Isles, 



GENUS 25. TROPIDONEIS 

 CLEVE, 1891. 



Valve very convex, carinate, with keel 

 not sigmoid, sometimes straight, sometimes 

 oblique. Median pores on the median line 

 very approximate. Axial hyaline area 

 absent ; central area absent or small. Striae 

 parallel, formed of small beads, forming also 

 more or less regular longitudinal lines : Con- 

 necting zone simple, without plaits. 



Fig- 53- Amphiprora 

 maxima. 



Sec. I. ORTHOTROPIS Cl., 1891. Central keel (straight), girdle 



face very strongly constricted. 



ANALYSIS OF SPECIES, 

 f A pseudo-stauros round the central nodule ; stria; rather robust 0. maxima. 

 < No pseudo-stauros ; strias delicate. . . .0. lepidoptera. 



| A true stauros ; valve simulating a navicula. 



V 



Pseudo-amphiprora staur- 

 optera. 



O. lepidoptera (Greg.) Cleve. (Diat. of Clyde, p. 33, pi. 4, 



f. 59 ; H.V.H. Atl., pi. 22, f. 2-3* ; Type No. 197), plate 5, fig. 287. 



Valve lanceolate, with apices acute and slightly apiculate. Central nodule 

 robust. Keel straight. Strise parallel, fine, 21 in 1 c.d.m. Frustule 

 elongate-linear, oblong, constricted at the median portion, with apices 

 rounded, slightly inflated. Length, 10 to 20 c.d.m. 



Marine. Washings of mussels (Deby.). England (Kitton, Norman) 

 (O'Meara), France ?, Holland. 



Scotland. Irelan 



