A Revision of the Genus Auliscus Ehrh., &c. By J. Eattray. 863 



2, rarely 1, 3 or 4, mastoid and low or mammillate and more elevated, 

 the free ends flat or convex, with central portion hyaline or punctate, 

 round, elliptical, or obtusely angular, their border hyaliae, rarely 

 striated, the circumference smooth or with minute irregularities. — 

 Bail, Smiths. Contrib., 1853, p. 4 ; CoscinocUseus pro parte Ehrb., 

 ibid. 1843, p. 271, 1844, p. 77 ; Klitz. Sp. Alg., p. 126 ; Masfoch'scus 

 Bail, ibid., p. 4 ; Eupodiscus pro parte Smith Syn. Brit. Diat. 

 vol. i. p. 25. 



§ 1. Granulati. 



Markings granular. No converging strias between central space 

 and processes. 



A. rohustus. 



A. punetaius var. rohusta Truan & Witr, Jerem. Diat. 1888, p. 12, 



pi. ii. fig. 9. 



Eoundly elliptical, major axis 0*1025 mm., about l^W times 

 minor. Surface with central portion indistinct, its edge convex 

 outwards between the processes about 3/4 of radius from border, slope 

 at border slight. Colour pale grey, darker at outer edge of central 

 portion. Central space rounded, • 01 mm. broad. Markings 

 prominent round granules, subequal, 3-^ to 4 in O'Ol mm., in 

 inconspicuous radiating and diverging rows. Processes 2, nearer 

 central space than border, irregularly round, about • 02 mm. broad, 

 their border wide, the central portion small, irregular. 



Habitat : Jeremie deposit, Hayti (Weissflog ! ). 



A. 2Muj)er sp. n., Sch. Atl,, pi. cxxv. fig. 5 (no name). 



Subcircular, diam. • 053 mm. Surface subplain, rising but 

 slightly at the processes, the transverse central area defined by a 

 distinct clear band, convex outwards between, and passing on central 

 side of, processes. Central space indefinite. Markings small, rounded 

 granular, chiefly on an irregular space around the edge of the trans- 

 verse area, and in loosely disposed radial lines outside of the clear 

 band, interspaces hyaline. Processes 2, subcircular, • 0125 mm. broad, 

 their border wide, circumference subsmooth. 



Habitat : Simbirsk (Thum). 



A. Rattrayi Cleve in litt. 



Eoundly elliptical, ma-jor axis * 06 mm., about ] l- times minor. 

 Surface subplain. Central space circular, 0'0075 mm. broad. 

 Markings round, granular, most evident towards the border, about 

 4 in • Oi mm., interspaces narrow, hyaline, Eows distinct, radial, not 

 converging around the processes. Processes 2, placed from 3/8 to 1/2 

 of distance between central space and border, their border broad, 

 irregular. — PL XII. fig. 2. 



Habitat: Barbadoes deposit (Cleve!). 



3 N 2 



