500 SYSTEMATIC PALEONTOLOGY 



at the margin of alternate sectors. Central space hexagonal, hyaline. 

 Diam. quite variable. 



This species is widely distributed both recent and fossil and is espe- 

 cially abundant in the Maryland Miocene. It appears to take the place 

 in the middle and upper beds of A. lieliopelta with which it may be con- 

 nected by the variety versicolor Brun. 



Occurrence. — 



Collection. — Maryland Geological Survey. 



ACTINOPTYCHUS VULGARIS VAR. VIRGINIAE GrunOW. 



Genus SCHNETTIA De Toni. 



ScHNETTiA AMBLYOCEROS (Ehrenbcrg). 



Family ASTEROLAMPRE/E. 



Genus MASTOGONIA Ehrenberg. 



.Mastogonia ACTINOPTYCHUS Ehrenberg. 



Mastogonia crux Ehrenberg. 



Mastogonia sexangulata Ehrenberg. 



Genus ASTEROLAMPRA Ehrenberg. 



AsTEROLAMPRA MARYLANDICA Ehrenberg. 



ASTEROLAMPRA DALLASIANA Grevillc. 



Family COSCINODISCE.^. 



Genus CRASPEDODISCUS Ehrenberg. 



Craspedodiscus coscinodiscus Ehrenberg. 



Plate CXXXV, Fig. 3. 



Craspedodiscus Coscinodiscus Ehrenberg, 1844, Monatsb. d. k. Akad. d. Wiss., Berlin, 



p. 266. 

 Craspedodiscus coscinodiscus Ehrenberg, 1856, Mikrogeolgie, pL 33, xvi, fig. 8. 

 Craspedodiscus microdiscus Ehrenberg, 18.56, Mikrogeologie, pL 33, xvii, fig. 84. 

 Craspedodiscus coscinodiscus Ralfs, 1861, Pritcbard's Infusoria, p. 832. 

 Craspedodiscus coscinodiscus Schmidt, 1875, Atlas der Diatomaceen-kunde, pi. Ixvi, 



figs. 3, 4. 



Description. — Valve circular, with sharply defined border equal in 

 width to the semi-radius. Central part with small central space and 

 somewhat indistinct hexagonal markings, 7 in .01 mm. Markings of 

 border hexagonal, 3 in .01 mm. Diam. .132 mm. 



Occurrence. — Calvert Formation. Fairhaven, Nomini Bay, God's 

 Grace Point, -J mile north of Forest Wharf, 1 mile north of Jewell, 1 mile 



