MARYLAND GEOLOGICAL SURVEY 115 



is a trifle more elongate than the same valve of C. martini, but the 

 principal difference lies in the marginal ridge which in that species is 

 generally confined to the ends. In the present species, however, the 

 ridge is distinguishable also along the ventral side, and moreover it is 

 a double ridge, to outer division gradually turning into a narrow flat- 

 tened border and thickening up again as it passes along the posterior 

 edge. The inner division starts at a small knob in the anterodorsal 

 angle and passes downward in a course paralleling the anterior edge 

 into the ventral region where it bifurcates, the lower division continuing 

 on and remaining parallel with the margin to the postcardinal angle, 

 a second bifurcation occurring as it passes the postventral angle. The 

 inner divison of the first bifurcation diverges at first slowly and then 

 more rapidly in its course to a point lying a short distance in front of 

 the postcardinal angle where it joins the upper extremity of the more 

 nearly vertical inner part of the second bifurcation. A rather distinct 

 though low and broad swelling of the surface occurs on the anterior half 

 of the surface and behind this a second but smaller elevation is distin- 

 guishable. Between the dorsal edge and the marginal ridge, and also 

 between the bifurcations of the latter, the surface is distinctly pitted, 

 the pits being small and elongate and exhibiting a tendency to longi- 

 tudinal arrangement. 



Length of a left valve 0.60 mm., greatest height of same 0.31 mm., 

 height of posterior extremity 0.20 mm. 



Named for Mr. E. Lienenklaus, of Osnabriick, Germany, whose 

 "Monographic der Ostrakoden des nordwest-deutschen Tertiars" is a 

 very capable piece of work. 



Occurrence. — Calvert Formation. Plum Point. 



Collection. — U. S. National Museum. 



Cythere peoducta n. sp. 

 Plate XXXVI, Fig. 17. Plate XXXVIII, Figs. 28-30. 



Description. —Thh species agrees in its more important characters 

 rather closely with C. martini and its allies, but is distinguished from 

 them all by its much greater proportional length, more nearly parallel 

 ventral and dorsal edges, in having marginal spines at both ends of the 



