262 



AMPHIPRORA. 



A. alata Klltz. (Baa, p. 107, pi. 3, f. 63 ; H.V.H. Atl., pi. 22, f. 11 

 and 12*; Type No. 195), plate 5, fig. 289. 



Valve linear elliptic, with apiculate apices. 

 Keel sigmoid, furnished with elongated dots, about 

 4 in 1 c.d.m., and having on each side a very 

 projecting sigmoid ala. Striae fine, punctate, about 

 14 to 16 in 1 c.d.m. Frustule generally torsive 

 in a longitudinal direction, oblong elliptic, deeply 

 constricted at the median portion, with rounded 

 apices, connecting zone showing numerous longi- 

 tudinal plaits. Length, 5 to 13 c.d.m. 



Fig. s 2 - 



Amphiprora alala. 



Marine and brackish water.- Antwerp, Blankenberghe, Heyst, 

 England, and on all the coasts of the North Sea. 



A. paludosa W. Sm. (S.B.D., i., p. 44, pi. 31, f. 269; h.v.h. Atl., 



pi. 22, f. 10*; Type No. 196), plate 5, fig. 290. 



Valve elliptic lanceolate, with apiculate apices. Keel sigmoid. Striae fine, 

 19 or 20 in 1 c.d.m. Frustule torsive, with girdle face deeply constricted at 

 the median portion, apices rounded or truncate, connecting membrane with 

 plaits fine, very approximate. Aire very projecting, forming near the apex 

 a plait, which, when seen in the girdle view, assumes the appearance of an 

 inflexion or undulation. Length, 4 to 8 c.d.m. 



Brackish water. Antwerp, Blankenberghe. England (Comber, Kitton, Stolt. , Norm., and 

 W. Sm.) and probably in all our regions. 



Observation, It sometimes happens that a number of stria; become more 

 vigorous than the others, as in the first of the two figures. 



var. duplex. (A. duplex Donk., T.M.S., 1858, vi., p. 28, pi. 3, f. 13; 

 H.V.H. Atl., pi. 22, f. 15, 16* ; in Type No. 416), plate 5, fig 292. 



Valve with keel very sigmoid, lateral alae with inflexion very feeble or 

 absent. Length, 4 to 6 c.d m. 



Marine. Blankenberghe (2nd basin). Rare. England (Comber and W. Sm.). 

 Ireland (O'Meara), and probably in all our regions. 



A. ornata Bailey. (Mic. Obs. made in South Carolina, etc., p. 38, 

 pi. 2, f. 15 and 2 3 ; H.V.H. Atl., pi. 22 bis., f. 5*), plate 5, fig. 293. 



Frustules torsive, deeply constricted at the median portion, with alas gently 

 undulate and festooned throughout their length. Striae radiate, finely punctate, 



