Neiu American Paleozoic Ostracoda. 



181 



Only one other species of Ctenobolbina is known having a 

 punctate surface ; this is a Niagara species to which I gave 

 the name C. punctata. The present form is relatively shorter, 

 less convex, and strikingly different in the outline of the 

 anterior half. The sulcus also is much less developed. 



Formation and Locality. — Rare on thin slabs of limestone, 

 from the lower portion of the Clitambonites bed of the Tren- 

 ton group at Kenyon, Minn. 



Ctenobolbina spiculosa, n. sp. 

 Plate VIII, Fig. 5. 



Size : Length, 1.65 mm. ; hight, with flange, 1.0 mm., with- 

 out flange, 0.8 mm. 



This fine species, although given a very different expres- 

 sion by its spinous surface, is nevertheless a close ally of C. 

 antespinosa, Ulr., with which it is also associated at the Falls 

 of the Ohio. Comparing the two species, we find that the 

 central tubercles and ridges of C. antespinosa are all repro- 

 duced in C. spiculosa, but in a more subdued form. The ver- 

 tical anterior ridge is represented by a couple of spines 

 merely. The posterior lobe, on the other hand, is more 

 prominent and drawn out above into a strong spine. All the 

 surface elevations are granulose in C. spiculosa, and, except- 

 ing one, spiniferous as well. Two bunches of spines occur 

 also near the post-ventral margin. The flange is wider in C. 

 spiculosa and merely convex instead of bent angularly, and 

 the valve, excluding the flange, more nearly equal-ended. 



For?nation and Locality. — From the Devonian (Hamilton 

 group) bryozoa bed at the Falls of the Ohio. 



Ctenobolbina armata, n. sp. 



Plate VIII, Fig. 6. 



Size: Length, 1.38 mm.; hight, 0.78 mm. 



This also is related to C. antespinosa, but is readily distin- 

 guished. The posterior sulcus passes completely through to 

 the flange, which, on the contrary, js a comparatively insig- 

 nificant feature. The lower portion of the posterior lobe is 

 raised into a compressed spine, projecting outward and down- 

 ward to the ventral margin. A similar but more prominent 



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