80 i Transactions of the Society. 



A. nanus, Sch. Atl., pi. xxxii. fig. 27. 



Siibcirciilar or elliptical, tliam. • 04 mm. Surface flat. Colour 

 hyaline, with dark border. Central space circular, hyaline, incon- 

 spicuous, about ■ 003 mm. broad. Markings round, granular, minute, 

 with wide interspaces, irregular or in faintly marked radiating lines 

 curved towards the processes, sometimes absent between the processes 

 and the central space, and for a distance of about • U025 mm. from 

 each process. Processes 2, subcircular, 0'005 mm. broad. 



Habitat: Cambridge de^wsit, Barbadoes (Johnson!); Simbirsk 

 Polirschiefer (.Schmidt). 



A. Clevei Grun., Sch. Atl., pi. xxxi. figs. 1-4. 



Elliptical, major axis 0*06 mm., about li times minor. Surface 

 rising suddenly to the processes, a narrow, clear, parallel band passing 

 between the b.ise of the processes on each side of the central space. 

 Colour pale grey. Central space rounded, • 0075 mm. broad. jMarkings 

 rounded, distinct, 8 in 0"01 mm., smallest towards central space, 

 arranged in lines radiating and diverging from the central space to 

 the border, and concave towards the processes, absent from a narrow 

 area at base of processes. Processes 2, about 0"005.j mm. broad at 

 the base, free ends rounded, in girdle aspect conical, rising to about 

 0"0125 mm. above edge of girdle. 



Habitat : Campeachy Bay ( Weissflog ! Cleve !). 



§ 2. Striolati. 



No transverse median areas. Markings delicate, straight, flexuous 

 or uniformly curved, striae usually inconspicuous. Apiculi minute or 

 prominent, irregularly scattered, sometimes confined to distinct areas, 

 rarely absent. 



A. pressus Leud.-Fort. Diat. Ceyl., p. 63, pi. vii. fig. 72. 



Irregularly elliptical with obtuse extremities, major axis about 

 0-045 mm., 1|- times minor. Surface with low processes, slope at 

 border slight. Central space circular, about 0"003 mm. broad, 

 distinct. Markings irregular, flexuous, but evident, short striae 

 radiating from the central space towards the border, those converging 

 to the processes inconspicuous, urregular. Processes 2, subcircular, 

 about • 0055 mm. broad, their central portion distinctly punctate. 



Habitat : Ceylon (Leuduger-Fortmorel). 



A. nitidus sp. n. 



Elliptical, major axis • 0625 mm., 1;^ times minor. Surface almost 

 flat. Colour suljhyaline. Central space diamond-shaped, indistinct, 

 minute, with straight sides, the angles in the direction of the processes, 

 and of the minor axis. Markings obscure, punctate, isolated delicate 

 puncta around the outer edge of the central space, a few delicate striae 



