494 SYSTEMATIC PALEONTOLOGY 



BiDDULPHIA GRANULATA Eoper. 

 BiDDULPHIA INTERPUNCTATA (Grunow). 



Plate CXXXIV, Fig. 9. 



Triceratium inter punctatum Grun., Scbmidt, 1875, Atlas der Diatomaceen-kunde, 



pi. Ixxvi, flg. 7. 

 Biddulphia interpunctata Boyer, 1901, Proc. Acad. Nat. Sci. Phila., vol. lii, p. 722. 



Description. — Valve triangular with straight sides and rounded an- 

 gles. Surface flat with rounded puncta, 3 in .01 mm. with much smaller 

 puncta at intervals. L. of s. .075 mm. to .115 mm. Color blue, under 

 low powers. 



Occurrence. — Calvert Formation. ^ mile north of Forest Wharf, 1 

 mile north of Jewell, 1 mile northwest of West Eiver, 1 mile south of 

 Chesapeake E. E. Bridge, 1 mile north of Jones Point. (Eather com- 

 mon.) 



Collection. — ^Maryland Geological Survey. 



BiDDULPHIA MOBiLiENSis Bailey. 



BiDDULPHIA QUADRICORNIS (GrunOw). 



BiDDULPHIA RETICULUM (Ehrenbcrg). 



BiDDULPHIA SEMICIRCULARIS (Brightwcll) . 



Plate CXXXIV, Fig. 10. 



Triceratium semicirculare Brightwell, 1853, Quart. Jour. Roy. Mic. Soc. vol. i, p. 



352, pL iv, fig. 21. 

 Triceratium ohtusum Ehrenberg, 1856, Mikrogeologie, pi. xviii, fig. 49 (in part). 

 Triceratium semicirculare Van Heurck, 1881, Syn. Diat.-Relg., pi. cxxvi, fig. 20. 

 Biddulphia semicircularis Boyer, 1901, Proc. Acad. Nat. Sci. Phila., vol. lii p. 726. 



Description. — Valve lunate, appearing as if divided half-way between 

 the center and the obtuse ends by two very faint costate lines. Surface 

 elevated at the center and at the ends, with rounded puncta, about 3 in 

 .01 mm., concentric and radiating from a hyaline center, smaller at the 

 ends. L. of s. av. .099 mm. 



Occurrence. — Calvert Formation. ^ mile north of Forest Wharf, 

 Nomini Bay, Chesapeake Beach, God's Grace Point, Fairhaven, 1 mile 

 west of Tracy Landing, 1^ miles southeast of Marriott Hill, 1 mile 

 north of Jewell, 1 mile north of Jones Point, 1 mile south of Chesa- 

 peake E. E. Bridge, 1 mile northwest of West Eiver, 1 mile east of 

 Marriott Hill. 



Collection. — Maryland Geological Survey. 



