Beede: New Species of Fossils 



7 



convex, rounding rather more gradually than usual into the truncated 

 posterior, which is inclined somewhat forward and is subelliptical in cross- 

 section. The lunule is narrowly elliptical and nearly horizontal, otherwise, 

 as in the other species. The escutcheon is apparently shorter, narrow, and 

 better defined than in most of the other species. It is well set off by a sharp 

 ridge on each valve. The ridges nearly meet posteriorly, giving it a lanceolate 

 form. The valves are thickest posteriorly, the shell narrowing toward the 

 front. The umbonal ridge is subangular toward the beaks, becoming more 

 rounded below, but persisting as a ridge to the postero-ventral angle of the 

 shell. It also falls more rapidly than in some species of the genus, making 

 a wider area above it. At the same time the undulations of growth which 

 are fairly well impressed upon the body of the cast are traceable over this 

 area, being nearly as distinct as on the body of the shell. Muscle 

 marks and pallial line are not shown. Length of shell about 60 mm. ; height 

 about 30 mm.; beak 17.5 mm. from the anterior end; length of hinge 43 mm.; 

 transverse diameter 22 mm., near the middle of the shell. 

 Florena shale; Grand Summit, Kansas. 



This species differs from C. leavenworihensis Meek and C. cylindrica in 

 its straighter cardinal margin and better defined escutcheon, as well as the 

 wide region above the umbonal ridge. The truncation is somewhat more 

 oblique and more widely gaping than in C. harbouri. The undulations are 

 stronger than on any of the other species of the genus except C. miimehaha 

 (Swallow) . 



Chaenomya johnstoni n.sp. 



The shell is rather large, hardly twice as long as high, with the beaks 

 about a fourth the length of the shell from the front end. The umbonal 

 region is rather high, the front broadly rounded and passing gradually into 

 the gently convex base. Posteriorly the ventral margin rounds rather grad- 

 ually into the oblique posterior truncation. The dorsal margin is relatively 

 short and quite concave. The beaks seem to have been practically in con- 

 tact, as is not uncommon in some of the species of the genus. The umbonal 

 ridge is well defined near the beaks and remains rather high to the central 

 part of the posterior end of the shell, which is widely gaping. The opening 

 is broadly ovate in form. The surface is marked with rather fine undulations 

 of growth and rows of strong granules radiating from the beaks. Length 

 76 mm.; length of hinge 53 mm.; beaks 18.5 mm. from the front end; height 

 39 mm.; diameter of the shell in the thickest part near the beaks 29.5 mm.; 

 a line from the beak to the postero-ventral margin is 70 mm. long. 



Shale on the Americus limestone; two and a half miles southwest of 

 Americus, Kansas. Harry Johnston, collector. 



This shell differs from C. leavernvorthana Meek in being longer from the 

 beak to the postero-ventral angle, in possessing rows of coarse granules 

 rather than fine ones, and in possessing a more gentle slope at the lunule, 

 giving a broader aspect to the anterior end of the shell. 



Myalina shannoni n.sp. 



The shell is large, subquadrate in form, and is quite thin when compared 

 with M. suhguadrata. The hinge is apparently as long as the shell at any 

 place beneath it. The ventral margin is so thin that it is preserved in none 



