LAMELL1BRANCHIA TA. 
513 
* This species bears some general resemblance to the fossil referred to Solemya 
vetusta, especially in the fold of the shell on the upper anterior margin, and it 
may prove congeneric with that form. 
Formation and locality. In the cherty layers above the Hydraulic limestone, 
near Louisville, Ky. 
Clinopistha telliniformis. 
PLATE LI, FIGS. 28-31. 
Dystactella telliniformis, Halt,. Pal. N. Y., vol. v, pt. I. Plates and Explanations : PI. 51, figs. 28-31. 1883. 
Shell large, obovate; length less than twice the height. Basal margin gently 
curved, nearly straight anterior to the middle. Posterior end large and 
rounded. Cardinal line arcuate. Anterior end produced, nasute, obliquely 
truncate above. 
Yalves gibbous in the middle and nmbonal region. 
Beaks behind the anterior third, not prominent. Umbonal slope rounded, 
not defined. Umbo flattened in the middle and the flattening continued 
vertically to the base. On the anterior end there is a distinct angular ridge 
on each valve, extending from the beaks to the antero-inferior extremity. 
Surface marked by fine striae of growth very obscurely preserved in the 
specimens described, which are casts of the interior. Interior unknown. 
A large specimen has a length of 65 mm. and a height of about 38 mm. 
An imperfect specimen has a height of 35 mm., a length anterior to the beaks 
of 30 mm., and the depth of both valves is 26 mm. A small individual 
measures 38 mm. in length, 20 mm. in height, and the depth of both valves 
is 18 mm. 
This shell is much larger than the preceding species, the anterior end is more 
produced, and the valves are more gibbous. 
Formation and locality. In the limestone of the Upper Helderberg group, 
Cayuga, Ontario. 
