MARYLAND GEOLOGICAL SURVEY 497 



Genus ENCAMPIA Ehrenberg. 



Encampia zodiacus Ehrenberg. 



Genus DISCOPLEA Ehrenberg. 



DiSCOPLEA GRANULATA Ehrenberg. 



Family EUPODISCE^E. 



Genus AULISCUS Ehrenberg. 



AuLiscus CABALLi Schmidt. 



AuLiscus PRUNOSUS Bailey. 



Genus PSEUDAULISCUS Leuduger-Fortmorel. 



PsEUDAULiscus spiNosus (Christian). 



Plate CXXXV, Fig. 10. 



Aulucim spinoms Christian, 1887, The Microscope, fig. p. 68. 



Pseudauliscus spinoaua Rattray, 1888, Quart. Jour. Roy. Mic. Soc, Londori, vol. ii, 

 p. 44. 



Description. — Valve suborbicular, with a broad border nearly half the 

 radius in width, separated from central part by a well-defined line. 

 Markings about 10 in .01 mm., irregular at the center and radiating in 

 curved lines toward the circumference, alternate rows on the border more 

 evident, curving inwards near the ocelli. Margin striated. Ocelli cir- 

 cular, near the edge. A number of small spurs are found outside of the 

 intermediate ring. On opposite sides half-way between the ocelli one 

 or two small spines are seen. Diam. .OoG to .171 mm. 



Occurrence. — Calvert Formation. Fairhaven, 1 mile northwest of 

 West Eiver, Cambridge Artesian Well, liare. In the artesian well 

 deposit of Mays Landing, New Jersey, the valves are quite large and not 

 uncommon. 



Collection. — Maryland Geological Survey. 



Pheudauliscus radiatus (Bailey). 

 PsEUDAULiscus RALFSiANus (Grcville). 



Genus AUi.ACODlSCUS Ehrenberg. 



AuLACODiscus ROGERSii (Bailey). 

 Plate CXXXIV, Fig. 5. 



Poducus Itofjersii Bailey, 1844, Amer. Jour. Sci., vol. xlvi, p. 137, pi. ill, figs. 1, 2. 

 Aulacodiscus Rogernii Schmidt, 1875, Atlas der Diatomaceen-kunde, pi. evil, fig. 3. 

 AulacodUcus Rorjersii Rattray, 1888, Quart. Jour. Roy. Mic. Soc, London, ser. ii, 

 vol. vili, pi. 372. 



Description. — Valve circular, flat at center and then rising to near the 

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