ORTHONEIS. 



283 



Valves elliptic, having 12 or 13 stria? in 1 c.d.m. ; the upper showing on 

 one margin a hyaline space in the form of a horse shoe ; the lower with 

 median stria; much shortened, and forming a pseudo-stauros. Length, - 8 to 

 2 c.d.m. 



Fresh water. Rather rare. Antwerp, Brussels (H.V.H.), Ard. Lieg. (De Wild.). France, 

 England (Comber, Norman), Ireland (O'Meara). 



var. dubia. (H.V.H. Atl., pi. 27, f. 12 and 13*; Type No. 236), 

 plate 8, fig. 337. 



Differs from the type form by its stria; somewhat closer, about 13 to 14 

 in 1 c.d.m., by its lanceolate form, with produced rostrate apices, and by 

 its somewhat shorter pseudo-stauros. Length, about 1*5 c.d.m. 



Fresh water. Brussels (Delogne). 



Tribe V. Cocconeide^. 



' Valves furnished with short marginal costae 



Valve 

 without 

 marginal 



costae. 



Frustules straight on girdle view, raphe eccentric 



Orthoneis, 

 Anorthoneia. 



Raphe dividing 



the valve into 



two equal 



portions ; 



girdle face 



flexed. 



' Valves simple, dissimilar, the upper having 

 only a pseudo-raphe ; the lower having 

 nodules and a true raphe , . Cocconeis. 



1, The lower valve composed of two layers ; 

 the upper consisting of a framework of 

 robust costpe, that underneath consisting 



of a normal valve 



. Campyloneis. 



GENUS 31. 



ORTHONEIS GRUN., 1868. Emend 

 Grun., 1880. 



Fig. 62. Orthoneis splendida (Greg.) Grun. 



(a) Upper valve. 



(<5) Annulus and direction of raphe on the two valves. 



Valves similar, furnished with a marginal crown of short costae, 

 sometimes without hemispherical layers. Frustules not flexed on the 

 girdle side, 



