A Revision of the Genus Aulacocliscns Ehrb. By J. Rattray. 371 



with two opposite sides straight, convergent, the third convex between 

 the closer ends of former, the fourth concave. Markings polygonal, 

 without interspaces, 4 to 5 in • 01 ram., outlines faint, those on 

 highest zone more distinct, rows straight, radial. Primary rays only 

 recognizable with difficulty when traced inwards from processes. 

 Border indistinct. Processes 10, insertion about 5/16 of radius from 

 circumference, of these 5 are at the angles of the highest zone, the 

 others at a slightly higher level at middle or somewhat towards one 

 side of intervening area. The processes are broken off, leaving a 

 round scar. 



Habitat : Cambridge deposit, Barbadoes (Johnson ! Greville !). 



§ 10. Eetiformes. 



Markings small, round or oval, rarely angular, reticulum well 

 marked. Primary rays indistinct. 



A. reticulatus Pant., Fossil. Bacil. Ung., p. 60, pi. i. fig. 1. — Diam. 

 • 25 to • 275 mm. Surface rising gradually to zone within pro- 

 cesses, outer edge of this sharply defined, thence sloping steeply to 

 border. Colour pale grey, reticulum and border darker. Central 

 space angular, 1/27 to 1/33 of diam. broad, punctate. Markings 

 mostly round or oval and oblique, rarely angular, 4 in • 01 mm,, 

 outlines indistinct, rows straight, deflected at processes, beyond highest 

 zone moniliform, interspaces punctate, largest at origin of shorter 

 rows, at outer edge of highest zone a narrow band 1/10 to 1/11 of 

 radius broad, with markings similar to, but inversely more or less 

 crowded than, those on rest of valve ; reticulum with meshes large, 

 irregular, long axis radial, indistinct on outer portion of highest zone, 

 a well-marked single or double band at border with division lines 

 radial. Primary rays inconspicuous, traceable to central space or to 

 more irregularly marked surrounding area. Border stria? 8 to 10 in 

 0*01 mm., about 1/55 of radius broad, outer edge sometimes inflected 

 at lines of reticulum. Processes (?), insertion about 1/5 of radius from 

 circumference, large, proximal part evanescent, constriction distinct, 

 free ends truncate or slightly emarginate, clear space at base small. — 

 Sch. Atl. pi. cii. fig. 7. 



Habitat : Szent Peter and Szakal deposits (Pantocsek !). 



A. Grunoivii Cleve, Journ. Quek. Mic. CI., 1885, p. 171, pl.xii. 

 fig. 8. — Diam. 0' 14 to 0'315 mm. Surface slightly convex and ele- 

 vated to about 5/8 of radius, and thence along primary rays to 

 processes, with outer edge concave outwards on compartments, at 

 border flat, in larger valves flat to about 7/19 of radius, thence rising 

 to highest zone, which is about 4/19 of radius broad. Colour grey, 

 raised areas lighter in hue. Central space irregular, indistinct, 1/23 

 to 1/33 of diam. broad, punctate. Markings round, granular, oval 

 about primary rays and polygonal near border, interspaces unequal, 

 largest towards central space, punctate, rows radial, straight ; reticu- 

 lum with large meshes, less evident outside highest zone, at outer 



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