A Revision of the Genus AuUscus Ehrh., &c. By J. Eattraij. 865 



between the central space and the processes; sparsely disposed, 

 irregular, minute, clear specks chiefly towards the border. Processes 

 2, close to major axis of valve, circular, O'Ol mm. broad, with wide 

 border.— PL XII. fig. 4. 



Habitat : Newcastle deposit, Barbadoes (Firth !). 



A. harhadensis Grev., Trans. Mic. Soc. Lond., 1865, p. 5, pi. i. fig. 1. 



Elliptical, major axis 0*05 mm., about 1^ times minor. Surface 

 highest and slightly convex along the line of the processes, slope at 

 border gentle. Colour subhyaline. Central space subcircular, distinct, 

 about • 003 mm. broad. Markings obscure ; the two narrow, irregular, 

 clear bands passing obliquely between the central space and the border 

 on each side of the striae convergiug to the processes, curving and 

 branching towards their outer ends. Processes 2, placed close to the 

 major axis, about • 0075 mm. broad. 



Habitat : Cambridge deposit, Barbadoes (Johnson ! ) ; Newcastle 

 deposit, Barbadoes (Weissflog !). 



A. lineatus Grrove & Sturt, Journ. Quek. Mic. CI., 1887, p. 141, 

 pi. xii. fig. 36. 



Eoundly elliptical, major axis 0*065 to O'l mm., about 1^ to 

 IjJg times minor. Surface rising gradually to the processes, and 

 sloping gently to the border, three distinct ridges diverging from the 

 angles of the central space, and dividing the area between the pro- 

 cesses on each side into four subequal portions. Colour pale smoky 

 grey. Central space irregular to hexagonal, from • 0075 to • 1 mm. 

 broad. Markings granular, scabrous, in flexuous, somewhat curved, 

 short striae placed obliquely to the ridges, and converging around each 

 process, elsewhere irregular, around the border an inconspicuous circlet 

 of more distinct granules. Processes 2, large, obovate, • 02 to • 025 

 mm. broad, their border with distinct strias, their central portion 

 minutely punctate. — Not A. fenestratus Grove & Sturt, Sch. Atl., 

 pi. cxxv., fig. 13. 



Habitat: Oamaru deposit (Grove and Sturt! E. Eattray! 

 Doeg ! Cleve !). 



A. parvulus Grev., Trans. Mic. Soc. Lond., 1863, p. 74, pi. v. 

 fig. 22. 



Subcircular, diam. ' 0325 to • 0375 mm. Surface flat. Colour 

 subhyaline. Central space inconspicuous, diamond-shaped, with sides 

 concave and angles protruding, about • 003 mm. broad. Markings 

 obscure, minute, punctate. Processes 3 or 4, subcircular, about 0*005 

 to • 006 mm. broad, their circumference with minute irregularities. 



In a valve with 3 processes these are somewhat larger, the central 

 space is still more indistinct and triangular. 



Habitat : Cambridge deposit, Barbadoes (Johnson !). 



