204 ILLINOIS STATE ACADEMY OF SCIENCE 



Remarks: — This species is more closely related to Cranaena iowensis, de- 

 scribed by Calvin from the Cedar Valley limestone in Fayette County, Iowa, 

 than to any other known species. At the type locality in Iowa the shells of 

 Cranaena iowensis are commonly much larger than the most of those belonging 

 to that genus at the Illinois locality from which our specimens were collected. 

 Besides the smaller size the shells of our species are much more triangular in 

 outline, the beaks more attenuate, and the greatest width of the shell much 

 feirther anteriorly than in Cranaena iowensis. Associated with Cranaena subo- 

 vata are shells which in form resemble Cranaena iowensis, and are referred 

 to that species although they are much smaller in size. 



Horizon and Locality: — Abundant in the Cedar Valley limestone a few feet 

 above the Acervularia davidsoni coral reef, a short distance west of Andalusia, 

 in Rock Island County. 



CRANAENA ELLIPTICA N. SP. 

 Plate II, Figures 3 and 4. 

 Description: — Associated with Cranaena subovata, and Cranaena iowensis 

 at the locality last mentioned are shells belonging to the genus Cranaena 

 which differ from either of the above mentioned species in their more elliptical 

 outline, the greatest width being at or posterior to the mid-length; the cardino- 

 lateral margins are straight, and form an angle of about 90 degrees at the 

 beak. An average individual has a length of 15 mm., a width of 14 mm. and 

 a thickness of 10 mm. The surface is marked by numerous, rather fine con- 

 centric lines near the front and lateral margins, the anterior margin is trun- 

 cated, and there is no trace of mesial fold or sinus. These shells have every 

 indication of being fully grown and it is proposed to designate them by the 

 name of Cranaena elliptica. 



CRANAENA MAXIMA N. SP. 

 Plate IL Figure 11. 

 Among the shells of the species of Cranaena above mentioned there are 

 occasionally found shells that rather closely resemble Cranaena iowensis 

 in outline, but are readily distinguished from any described species of the 

 genus by their very large size. The individual figured measured 40 mm. 

 long, 32 mm. wide, and 15 mm. thick. Such shells may be approximately 

 referred to as Cranaena maxima. 



CYPRICARDINIA ORNATA N. SP. 

 Plate II, Figure 8. 

 Description: — Shell small, subquadrate to rhombic-ovate in outline; hinge 

 line straight, about half the greatest length of the shell; beaks situated near 

 the anterior margin, directed forward, incurved so that they rise but slightly 

 above the hinge line. The right valve is rather strongly convex; the anterior 

 end short, concave immediately below the beaks, rounding to the basal margin 

 which is straight or very gently convex, and slightly indented a little anterior 

 to the middle. The postero-ventral extremity rounded, above which the pos- 

 terior margin is obliquely truncate, the surface is most convex in the umbonal 

 region from which it curves rather steeply to the front margin, and more gently 

 towards the hinge line; a shallow depression with poorly defined borders ap- 

 pears near the beak and extends obliquely over the somewhat flattened umbo 

 and on to near the middle of the basal margin. A rather prominent elevation 

 extends from the dorsal or posterior margin of the umbo obliquely backward, 

 with decreasing prominence to the postero-basal extremity of the valve; from 

 this elevation the surface curves rather steeply towards the dorsal margin where 

 the shell is somewhat flattened. 



The surface of the valve is marked by prominent, somewhat unequal con- 

 centric lines, about 5 mm. apart. The concentric lines, and less distinctly the 

 separating furrows, are crossed by two sets of fine striae, one set of which ap- 



