160 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxx. 



oped only in old specimens, is directly over the hinge but runs more 

 or less within the free edges. Test reticulated, the pattern moder- 

 ately fine. Free margins, ridges, and surface ornament all arranged 

 more or less obviously in a concentric manner. " Pit" of moderate 

 size though readily distinguished from the meshes of the surface orna- 

 ment, situated at the base of the median node and very near the center 

 of the valve. 



Fully developed and perfect examples present a ver}'^ distinctive 

 aspect. The concentric thin ridges and general form recall the Silurian 

 Strepala concentrlca Jones, ))ut taking into account onl}" the more 

 essential characters, the true alliances of the species are readily appar- 

 ent. These are doubtless with Kh'lhya trlcoUina Jones and Kirkbv, 

 a species originally described from the Lower Carboniferous lime- 

 stone of Great Britain and since found in the Birdsville formation of 

 the Chester in the Mississippi Valley. It also has 3 nodes on each 

 valve, but the central one is smaller and the lateral ones are not ridged, 

 while the valves are thinner and without the marginal ridge found on 

 K. centronata. 



Formation and locality. — Cottonwood shales, 2 miles east of Cotton- 

 wood Falls, Kansas. 



Holotype.—Q^i. No. 35628, U.S.N.M. 



Family CYTHERIDJE. 



Genus CYTHERE MuUer. 



CYTHERE ? HAWORTHI, new species. 



Plate XI, tig. 12. 



Length O.-iS mm., height 0.29 mm. 



Valves rather strongly convex, very slightly oblique, the posterior 

 half a trifle widei- than the anterior; dorsal edge long and straight, 

 cardinal angles distinct without being sharp; ends descending rather 

 abruptly from the extremities of the hinge, but curving broadh' 

 enough below into the ventral edge. Just behind and a little above 

 the center of the valves is a sharply defined and prominent round node; 

 another tubercle, more like a blunt spine and smaller, is situated near 

 the antero-cardinal angle. A third wing- like prominence marks the 

 posterior half of the ventral slope. Finall}-, a small swelling may be 

 observed at the post-cardinal angle. Nothing like a sulcus was observed. 

 Surface of test punctate, the puncta^ being arranged in somewhat 

 oblique longitudinal lines descending posteriorly. No pit, nor is there 

 a sign of a marginal rim. 



This minute ostracod is probably not a true Cytlxere., but its general 

 aspect suggests more of that famil}' than of Kirkbj'idfe. It is asso- 

 ciated with one or two other, apparently congeneric, species, while 

 still other forms of the same general type occur in the Upper Carbon- 

 iferous deposits of Texas. These should all be subjected to careful 



