Not Eupodiscus radiatus Wm. Sm, which is Biddulphia smithii (Ralfs) V. H.
Pl. [5], Fig. 3.
Auliscus Ehr. (1843)
(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, markings continuous, costate | sculptus cælatus |
AULISCUS PUNCTATUS BAIL.
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.
Port Penn, Delaware River. Rare.