2t> 



mesial sinus broad and deep. The minute surface characters 

 are unknown. The specimens are casts. 



This species bears some resemblance to 8. macropleura of 

 the Lower Helderberg group, of New York, but it is propor- 

 tionally more gibbous, the front more r egularly rounded, the 

 area higher, and the plications not directed so obliquely out- 

 wards from the beak. 



Geological Formation and Locality. Li limestone of the age 



♦f the Niagara group, Racine, Wisconsin. T. J. Hale. 



■ 



SPIRIFER INCONSTAN3, (n. 8.) 



Description. Shell transversely elliptical, the length a little 

 more than half as great as the width ; h inge line two-thirds as 

 long as the greatest width of the shell; cardinal extremities 

 rounded; both valves moderately conveix, marked by strong, 

 angular, dichotomizing plications. Dorsa I valve most prominent 

 on the umbones ; mesial fold broad and simple on some speci- 

 mens, and on others divided into two, thre e, or more plications in 

 front; beak produced and moderately incurved. Ventral valve 

 larger than the dorsal; beak prominent, but little incurved; 

 area high; deltidium large, hight and! width nearly equal; 

 sinus broad and deep, simple or with two or more plications. 

 Entire surface marked by strong, distinct, radiating striae. 

 The specimens are casts of the interior and exterior. 



This species may be readily distinguished from others by the 

 strong, angular, bifurcating plications, the number of which 

 vary in different individuals ; some being; nearly simple, having 

 but four or five on each side of the mesial fold, while others 

 have nearly double that number on the front margin. The 

 number of plications on the mesial fold and sinus are subject 

 to the same variation. 



Geological Formation and Locality. In limestone of the age 

 of the Niagara group, Racine, Wisconsin. Br. Hoy, T. J. 

 Hale. James Hall. 



'9 



TELLINOMYA inflate (n. s.) 



Description. Shell of medium size, extremely gibbous, and 

 inflated at the middle of the sides, abruptly attenuate towards 

 the posterior end; the length a little greater than the breadth, 

 and the thickness a little less: the hinge line, from a little 

 anterior to the beak to the posterior end of the shell, is nearlj 

 straight, the anterior end obliquely truncate above the middle, 

 the basal margin strongly and regularly rounded from the ante- 



