356 Transactions of the Society. 



§ 6. Mirabiles. 



Highest zone distinct, angular at processes. A reticulum or 

 irregular ridges. Primary rays indistinct within highest zone. 

 Border striae faint. Processes with clear area at base small. 



A. archangelshianus Witt., Sirnb. Polirsch., p. 18, pi. vi. figs. 11, 

 12. — Diam. ■ 1025 to ' 195 mm. Surface with highest zone at 1 /4 

 to 1/8 of radius from centre, primary rays rising slightly outwards; 

 inflations reaching border, compartments ilat near border. Colour in 

 lighter or dark grey zones. Central space angular, 1/16 to 1/33 of 

 diam. broad, clear. Markings rounded within highest zone and about 

 middle of compartments, elsewhere more crowded and angular, 6 in 

 0*01 mm., secondary oblique rows obvious on inflations which bear 

 irregular blunt ridges. Primary rays with rows widest about middle. 

 Border striae 12 in 0*01 mm., 1/20 to 1/30 of radius broad, with a 

 median line curving inwards at each inflation. Processes 5, rarely 6, 

 symmetrical, insertion 1/5 to 1/6 of radius from circumference, 

 proximal portion much larger than distal, constriction distinct, free 

 ends rounded. — Sch. Atl., pi. ci. figs. 7-11 ; Pant., Fossil Bacil. Ung., 

 p. 60, pi. x. fig. 83. 



Habitat : iSimbirsk Polirschiefer (Witt ! Cleve ! Kae ! Hard- 

 man !). 



A. superbus Kitton, Month. Mic. Journ., 1873, p. 205, pi. xxxviii. 

 fig. 1. — Diam. 0*175 mm. Surface with highest zone 1/17 of radius 

 broad at about 1/3 of radius from centre, from this the primary rays 

 continuing on same plane to processes; inflations reaching border, 

 merging gently into intervening areas. Colour pale grey, edges of 

 highest zone and inflations darker. Central space irregularly angular, 

 1/17 diam. broad, clear. Markings polygonal, rounded near centre, 

 6 to 8 in 0*01 mm., rows radial within, almost parallel outside of, 

 highest zone, secondary irregular concentric bands near central space. 

 Reticulum distinct, absent only from central space, highest zone, outer 

 ends of primary rays and border, meshes smallest towards centre. 

 Primary rays with rows diverging slightly near processes.- Border striae 

 6 to 8 in 0*01 mm., about 1/33 of radius broad, inner edge sharp. 

 Processes 7, insertion 1/12 of radius from circumference, sides con- 

 verging towards base, constriction slight, length 1| to 2 times 

 breadth. 



Habitat: Clark's Cliff,* Barbadoes (Kitton! Hanwell!); "Barba- 

 does " (Johnson) ; Upper Springfield, Barbadoes (Griffin !). 



A. attenuatus sp. n. — Diam. 0*1 to 0"105. Surface rising to 

 about semiradius, thence along primary rays to processes, edges of 

 inflations abrupt. Colour pale grey. Central space subregularly 

 polygonal, 1/13 to 1/14 of diam. broad, hyaline. Markings polygonal, 

 8 to 10 in 0*01 mm., rows parallel between inflations, a few at sides 

 of primary rays, parallel to the latter, a reticulum of subequal 



* According to label on Hanwell's material ; according to Kitton probably a mis- 

 take for Chalk Cliff. 



