434 



STEPHANOPYXIS. 



at the acute apices, having narrow margins, one of them (which I call the 

 upper) strong and coloured. Numerous transverse dissepiments occur 

 throughout the whole length, at irregular intervals, except for a space of 

 about 0014" in the middle, which is occupied by a smooth lamina, folded 

 up, as it were, and pressed against the surface, and so concealing the 

 dissepiments, convex above, where it is on a level with the coloured 

 margin, and gradually tailing off below into the uncoloured margin. Along 

 the upper margin are situated a row of very short stout subcapitate processes, 

 standing up like little nails, at irregular distances, evidently arising out of the 

 substance of the margin itself, and of the same colour, and having no 

 reference to the pseudo-dessepiments. The number of these processes varies ; 

 two generally, but sometimes three or four, belong to the centre, and between 

 the centre and each apex there are from 6 to 9. The valve is the view which 

 occurs most frequently, and strongly resembles a Ceratoneis, there being an 

 oblong inflation or expansion in the middle which passes suddenly into the 

 long exceedingly narrow sub-acute arms. The processes above described 

 appear in the view of the valve as strong, brilliant puncta, seated on one of 

 the margins ; but the puncta which occur in the centre or inflated portion 

 (nearly -0004" in breadth) are situated more or less in the middle of the space 

 and not on the margin." 



GENUS 103. STEPHANOPYXIS (HR, 1844), Char. 



emend. 



a. b. 



Fig. 158. Stephanopyxis corona. 

 a. Valve. b. Frustule. 



Frustules cohering by their 

 spines. Valves rounded or 

 elliptic, much inflated, with 

 structure usually cellular, with 

 either a central spine or 

 coronal or scattered spines, 

 very conspicuous. 



As I understand it, Cresivellia Grev. and Trochosira Kitt are included, 

 according to the above definition, in the genus Steplianopyxis. 



The species of this genus number more than 30, only one of which, 

 Stephanopyxis Turn's (Grev.), Ralfs {Cresivellia Turn's), H.V.H. Atl., p. 83ter., 

 f. 12*), appears to have as yet been found on the British Coasts. This 

 was found by Stolterfoth on the surface of the Dee, England, and by Norman, in 



