New American Paleozoic Ostracoda. 



183 



This also belongs to the C. antespinosa section of the genus, 

 and stands in some respects intermediate between that species 

 and C. cavimarginata. However, in views of the interior, 

 the broad concave flange reminds even more strongly of C. 

 spiculosa. The anterior ridge or tubercle of C. antespinosa is 

 present; also a rounded knob in the post-cardinal angle, 

 whose representative is more obscurely indicated in C. cavi- 

 marginata. The lobation of the central and posterior portions 

 of the valves agrees better with the conditions prevailing in 

 C. cavimarginata and C. armata than those marking C. ante- 

 spinosa, but, instead of rising into curved spines, the lower 

 portions of the posterior and anterior lobes are lost in the 

 convex flange. The latter is peculiar in two respects, first, 

 in the fact that its junction with the body of the valve is not 

 distinguishable externally, and, second, in its limited extent 

 and abrupt termination just in front of the middle of the ver- 

 tical edge. The contact edges around the ventral half are 

 finely toothed, a feature generally present in the typical sec- 

 tion of the genus, but otherwise unknown in this section. 

 The raised portions of the surface are more or less distinctly 

 granulose. 



Formation and Locality. — Same as the preceding. 



Ctenobolbina granosa, n. sp. 

 Plate VIII, Fig. 12. 



Size: Length, without flange, 1.0 mm.; hight, with flange, 

 0.68 mm., without flange, 0.58 mm. 



A rather small, convex and granulose species, with a sub- 

 central sulcus extending only about half across the valves, a 

 small longitudinal prominence just beneath it and a broadly 

 scalloped, delicate frill overhanging the post-ventral edge. 

 The latter is generally broken. C. bispinosa, from the Utica 

 group at Cincinnati, and C. punctata, from the Niagara group, 

 at Lockport, N. Y., are probably its nearest allies. 



Formatio?i a?id Locality. — Etched from limestone slabs con- 

 taining an abundance of br) ozoa received from Mr. Charles 

 Schuchert, who collected them from the lower Helderberg 

 formation, in Albany County, N. Y. 



5 



