2 66 



AURICULA. 



This singular form has all the appearance of a Nitzschia, and on first 

 examination is only distinguished from one by the central nodule being more 

 developed and the absence of dots on the keel. 



Marine. Coasts of England, Scotland, Denmark, France (Calvados), Oldenburg. 



PI. gibberula Grun. (H.V.H. Atl., pi. 22 bis., f. 12, 13* without 



description), plate 29, fig. 806. 



Valve lanceolate, narrow, with acute apices and margins abruptly gibbous- 

 inflated at the median portion. Striae fine, 18 in 1 c.d.m. Girdle face slightly 

 constricted, appearing at first view to be achnanthiform in consequence of the 

 presence of a projecting boss. 



Marine. Firth of Tay (Scotland). Heligoland. 



Sec. III. AMPHOROPSIS Grun. (in Syn. 1883). Valve with raphe 

 eccentric ; keels running in same direction. 



A. recta (Greg.) Grun. 



(Amphiprora recta Greg. T.M.S., 1857, 

 v., p. 56, pi. 1, f. 40; H.V.H. Atl., pi. 

 22 bis., f. 9-10. Cleve and Moll. Diat.) 



Frustules rectangular, gently con- 

 stricted at the median portion, with 

 rounded angles. Valve strongly unequi- 

 lateral, without distinct alae. Transveise 

 strise 21 to 24 in 1 c.d.m. Length, 8 to 9 

 c.d.m. Breadth, 2 to 3 cd.m. 



Marine. Mouth of the Tay, Scotland (Greg.) 



Fig. 55. Amplwropsis recta. 



Fig. 56.- 



GENUS 26. AURICULA CASTR, 1873. 



Valves very convex, extremely- 

 asymmetrical ; ventral and dorsal 

 portions in different planes. Raphe 

 raised like a keel, not sigmoid, 

 oblique. Keels of the two valves 

 turned on the same side. The two 

 terminal nodules connected by a semi- 

 mammiform elevation. Sutural zone 

 complex. 



The genus Auricula was created by 

 Count Castracane for a very curious form 

 -Auricula Ampiiitritis. found in the Island of Lesina in the 



