MARYLAND GEOLOGICAL SURVEY HI 



long, nearly straight in the middle, though on the whole gently convex 

 Anterior end with a narrow border that continues on around the ventral 

 side, but in a side view appears to die out before reaching half the dis- 

 tance to the posterior extremity. A similar but superimposed border 

 encloses the postventral portion of the valve, while just within is a 

 thm, raised line that above the posterior extremitv forms a distinct 

 margin to the anterodorsal region. Excepting the' marginal portions 

 and the compressed part of the posterior end, the entire surface is cov- 

 ered with^ minute pits, arranged more or less regularly in lines, many 

 of them disposed in a concentric manner. 



Length of a right valve 0.50 mm., greatest height of same 0.27 mm., 

 thickness of same 0.11 mm, 



A search of the literature has failed to reveal anv described species to 

 which this very neat little form might be referred. Of a number of 

 related species those which seem to offer the greatest degree of resem- 

 blance are two of the species described in this contribution, viz., our 

 C. piinctistriata and C. subovalis. As may be seen bv comparing the 

 figures of the three species on Plate XXXVIII, C. francisca is longer 

 and much more delicately pitted than C. suhovaUs. and further that it 

 has narrow rim-like borders that do not occur in that species. From 

 C. puncUstriata it differs decidedly in outline, the difference being par- 

 ticularly evident when the comparison is restricted to the anterior 

 halves. Then the surface ornamentation occupies a raised field in that 

 species and the pits, instead of occurring in concentric or irregular 

 rows, are placed in shallow, diverging furrows. 



The specific name is intended as a small tribute to Miss Francisca M 

 Wieser, who has shown rare ability and care in her work on the illus- 

 trations of the OsTRACODA described in this volume. 



Occurrence.— Choptank Formation. Peach Blossom Creek, 3 miles 

 southwest of Easton. 



CoUecUon.~U. S. National Museum. 



Cythere subovalis n. sp. 

 Plate XXXVIII, Figs. 14-15. 

 DescHpUon.~Leit valve moderately convex, with blunt edges, acumi- 

 nate-ovate in outline, the posterior end small, the anterior end broad. 



