Valve circular, 45-117 µ in diam. (De Toni). Central space absent, surface plane with angular cells. At the border short, circular processes or ocelli.
Valve with radiating hexagonal cells, sometimes slightly curved toward the large ocelli inserted near the border which are hyaline at the centre. Border wide, coarsely striate.
The number of ocelli heretofore recorded is four. Specimens with five processes are found in the artesian well at St. Augustine, Fla., and in material at Twelfth and Brandywine Sts. Mr. Hugo Bilgram has discovered valves with three and six ocelli.
Not common in the blue clay, but abundant along the southern coast of the Atlantic states and the Gulf of Mexico.
Not Eupodiscus radiatus Wm. Sm, which is Biddulphia smithii (Ralfs) V. H.
(aulax, a furrow, referring to the grooves in certain species, according to De Toni, but preferably from auliscos, a small reed, referring to the processes?)
Frustule cylindrical; zone with longitudinal rows of fine puncta. Valve circular or elliptical, plane except near the processes; central area hyaline, usually circular. Markings of two kinds, granules radiating or scattered and radiating, costate lines, prominent or indistinct. Processes, two or three, large, short, cylindrical, with hyaline surface, near the ends of the major axis in a line oblique to it.
Auliscus is divided by Rattray into fourteen sections, defined chiefly by the character and arrangement of the markings. About eighty species are described, but as many of the forms are fossil, occuring in the Miocene of California, Oamaru and elsewhere, and as so few species are found in this locality, I shall refer but briefly to this division.
_Striolati._--No transverse median areas, striæ inconspicuous punctatus
_Lineolati._--Markings distinct, pruinose, interrupted pruinosus
_Costati._--Transverse median areas usually distinct, sculptus markings continuous, costate cælatus
Valve broadly elliptical, or suborbicular, covered with delicate interrupted striæ radiating in sinuous lines to the circumference, more evident on the transverse median area; puncta 3 in 10 µ, grouped into a rounded area on each side of the median line, elsewhere scattered. Central space rounded, processes two, large, suborbicular.