900 Transactions of the Society. 



42. Vnlvo elonpittly dlipticjil 43 



„ sulicircular. Stritc delicate but little curved nuicraeanus. 



43. Outer eudd of transverse areas close to border ; stria? delicate, 



closely placed, convex to- 

 wards processes. Apiculifew ovalis. 

 „ „ „ not close to border; slriaj dis- 

 tinct. Apiculi minute, 

 chiefly on tninsverso areas 

 and around border .. .. pr.vlatus. 

 40. Processes 2, large, proximal portion obcouicul distal convex .. oamarueims. 

 No such processes 44 



44. A second elliptical area, with major axis transverse within 



outer larger transverse area lunatia. 



No such area present 45 



45. Transverse areas with a series of flcxuous stri."» around and 



almost parallel to their outer ends . . sculptus. 

 „ „ „ a faint reticulum at their outer ends. 



Striae continuous, punctate, distinct . cxlalus. 

 ^, „ „ markings in irregular plumose strands, 



a few irregular evident Ixuids passing 

 from the outer sides of these areas 



towards the processes suhcselutus. 



„ „ „ short distinct coAsb at tluii middle, 



and delicate curved diverging stria) 



ariiuud tlie sides gplendidits. 



„ „ „ striiB fine, distant, radial ; the intervals 



closely punctate rli'ipis. 



Striae throughout delicate, closely placed. Apiculi numerous, 

 most prominent on transverse area, valve elongately 

 elliptical Grevillei. 



PSEUDAULISCUS Sch. emend. 

 Fseudauliseus Sch. emend., Atl. Explan., pi. xxxii. figs. 28, 29. 



Valve circular, subcircular, or elliptical. Surface flat or with an 

 elevated zone within, more rarely outside of the processes. Colour 

 pale grey to pale smoky grey. Central space absent or minute. 

 Marldngs areolate, granular or punctate in radial, rarely in secondary 

 concentric or oblique rows, sometimes without order ; striae incon- 

 spicuous, sometimes converging around the processes or placed at a 

 distance from these; a reticulum rare; apiculi frequent, scattered 

 over the whole surface, or more rarely confined to the highest zone or 

 only near the border. Border narrow, hyaline or striated. Processes 

 2 to 9, rarely minute, round or elliptical, inserted close to the circum- 

 ference, then- border sometimes striated. — Lend. -Fort. Diat. Ceyl., 

 p. 64. Aidiscus pro parte Jan. Abh. Schl. Ges. vater. Cult., 1861, 

 p. 162. Eupodiscus pro parte Kitton in Pritch. Inf, p. 938. Grev. 

 Trans. Mic. Soc. Lond., 1861, p. 88. Cerataulus pro parte Grun. in 

 Sch. Atl., pi. CSV. fig. 10. 



Fseudauliseus amhiguus Grev., Trans. Mic. See. Lend., 1863, p. 74, 



pi. V. fig. 23. 



Pioundly elliptical, major axis 0'045 to 0-055 mm., about 1^- times 

 minor. Surface highest and shghtly convex between the processes, 

 thence sloping gently to the border. Colour hyaline. Markings 



