A Revision of the Genus AuUscus EJirh., &c. By J. Hattray. 909 



M. mammosa Grove & Sturt, Journ. Quek. Mic. CI., 1887, p. 142, 

 pi. xiii. fig. 38. 



Diam. from • 07 to • 1325 mm. Colour sometimes pink near 

 the process. Markings striate, striae 8 in O'Ol mm., sometimes 

 scabrous, the marginal band about 0*01 mm. broad, its inner edge 

 irregular. Process from 0"0125 to 0"0275 mm. broad. — Sch. AtL, 

 pi. cxxv. figs. 14, 15. 



Habitat : Oamaru deposit (G-rove ! Eae ! &c.). 



DEBYA gen. n. 



Valves circular. Surface fiat on central portion, slope to border 

 distinct. Colour pale smoky grey. Markings minute, punctate, in 

 radial lines, a reticulum sometimes present. Processes minute, 3 to 

 15, rounded or elliptical, between each adjoining pair 1 or 2 small 

 apiculi. — Glyj)hodiseus pro parte G-rove & Sturt, Journ. Quek. Mic. 

 CL, 1887, p. 10. Grun. in Sch. AtL, pi. csxv. Eupodisous pro parte 

 Grun., Bot. Centralbl., Bd. xxxi. No. 5, 1887, p. 133. Sch. AtL, 

 pi. Ixxx. 



D. oamaruensis. — Eupodiscus oamaruensis Grun., Bot. Centralbl., 

 Bd. xxxL No. 5, 1887, p. 133. 



Diam. 0"06 to 0*095 mm. Surface almost flat from centre for 

 about 5/18 of radius, slope to border steep. Colour most opaque around 

 the flat central portion. Markings in faint radial lines ; a reticulum 

 sometimes distinct, with meshes 3^ to 4 in • 01 mm., diminishing some- 

 what towards the border. Processes distinct, • 0035 mm. broad. Height 

 of centre above edge of girdle 0*025 mm. — Glyijliodiscus scintillans 

 Grove & Sturt, Journ. Quek. Mic. CL, 1887, p. 10. Eupodiscus 

 simlirskianus Grun., Bot. Centralbl., Bd. xxxi. No. 5, 1887, p. 133. 

 Sch. AtL, pi. Ixxx. fig. 8. GlypJwdisGus (?) simhirskianus Grun. in 

 Sch. AtL, pl. cxxv. figs. 18 a-e, 19. G. (?) oamaruensis Grun. in 

 Sch. Atl., pl. cxxv. fig. 20. 



Habitat : Sysran deposit, Simbirsk (Dcby !) ; Oamaru deposit 

 (Grove ! Hardman !). 



EUPODISCUS Ehrb. emend. 



Eupodiscus Ehrb. emend., Mon. Ber. Ak , 1844, p. 73. 



Circular. Surface fiat or slightly convex, the centre sometimes 

 slightly depressed. Colour pale to dark grey. Central space and 

 rosette absent. Markings areolate, subequal or decreasing from the 

 centre outwards, rarely smallest at the centre ; rows radial, straight 

 or curved, sometimes fasciculate or subradial, concentric, or without 

 order ; oblique decussating rows sometimes manifest, a distinct band 

 surrounding each process rare ; apiculi few or more numerous, and 

 forming a circlet close to the border. Border narrow and hyaline, or 

 with delicate striae, and sometimes broad and more prominent, with 



3 Q 



