A Revision of the Genus Aulacodiscus Ehrb. By J. Rattray. 355 



about 1/11 of radius from circumference, short but stout, length sub- 

 equal to breadth, space at base small, punctate. — PI. VI. fig. 2. 



Habitat: Jackson's Paddock, Oamaru (Kinker! Hardman! 

 Grove !). 



§ 5. Septati. 



Surface of 3 portions — a central triangular, rarely elliptical, 

 sharply defined, sides convex outwards, with angles at primary rays, a 

 median highest, convex, bluntly angular, with outer edge more faint, 

 an outer sloping gradually to border. Colour pale grey. No central 

 space or rosette. Processes with clear space at base large, V-shaped. 



A. septus Sch. Atl., pi. xxxvi. figs. 19-21. — Diain. 0-035 to 

 - 04 mm. Surface, central area sometimes elliptical with ends of 

 major axis at primary rays, extending for 3/8 to 5/14 of radius 

 median about 1 /6 of radius broad. Markings on central area polygonal 

 outlines faint, irregular, 6 in O'Ol mm., with a few small round 

 isolated granules, from median area decreasing slightly outwards, 8 in 

 ' 01 mm. Primary rays sometimes interrupted, the rows prolonged 

 past sides of processes to border. Border striae 8 in 0" 01 mm., 1/14 

 to 1/16 of radius broad. Processes 2 or 3, insertion 1/3 to 1/4 of 

 radius from circumference, as obovate dark spots. 



Habitat : Simbirsk Polirschiefer (Witt ! Weissfiog !). 



A. Schmidtii Witt., Simb. Polirsch., p. 21, pi. vii. figs. 1, 2. — 

 Diam. ■ 07 to • 1025 mm. Surface, central area flat, rarely lowest 

 at centre, extending for about 1/3 of radius, median portion 1/3 to 

 1/4 of radius broad, with angles passing round outer side of processes. 

 Markings on central portion polygonal, subequal, 4 in 0*01 mm., 

 forming straight rows near and at right angles to its edge, the round 

 isolated granules placed about its middle, on median and outer 

 portions round or compressed, 4 in ■ 01 mm., rows straight only 

 at middle of compartments, elsewhere curving towards processes. 

 Primary rays absent. Processes 3, insertion 2/5 of radius from cir- 

 cumference, narrow margins, concave, free ends rounded, length 3 to 5 

 times breadth. — Sch. Atl., pi. ci. figs. 1-3. 



The scar of the broken-off process is elliptical. 



Habitat: Simbirsk Polirschiefer (Witt! Weissfiog! Hardman!). 

 Sysran deposit, Siberia (Grove !). 



Var. quatuor-radiata. A. septus forma quatuor-radiata Pant., 

 Fossil Bacil. Ung., p. 60, pi. x. fig. 84. — Diam. ■ 0875 mm. Surface, 

 central area rounded, flat, highest, extending to 5/17 of radius, 

 adjacent zone hyaline, median portion quadrate. Markings on central 

 portion reniform, irregular, outside hyaline zone round or oblong, 4 to 

 6 in 0*01 mm. Border indistinct. Processes 4, insertion about 5/18 

 of radius from circumference, minute. 



Habitat : Simbirsk Polirschiefer (Pantocsek !) 

 By discovery of additional specimens A. Schmidtii may be shown 

 to be but a var. of A. septus, as A. KinJceri and A. Mblleri are of 

 A. margaritaceus. 



2 o 2 



