Raymond: Fauna of the Allegheny Series. 153 



Class Amphineura. 



Suborder Eoplacopora Pilsbry. 



Family GRYPHOClllTOXIDiE Pilsbr>'. 



Glaphurochiton genus nov. 



Oval, depressed chitons with granular surface, short and wide valves, 



the terminal margins of anterior and posterior valves depressed, the sinus 



slight or absent. Sutural lamin^t small, the valves without lateral areas 



and not laterally excavated. Mucro of tail-val\e at or bihind the middle. 



Type, Chiton carhonarius Stevens. 



Glaphurochiton carbonarius (Stevens). 



Plate XX\'I, figure 6; Plate XXVIII, figures 15, 16. 

 Chiton carbonarius Stevens, American Journal of Science, (2), XXV, 1858, 264. 

 — Meek and Worthen, Geological Survey Illinois, V, 1873, 608, pi. 29, figs. 

 I5a-i5h. 



Three specimens belonging to this species have recently been found in 

 western Pennsyh-ania. One from the Ames limestone at Summerhill 

 shows the anterior and posterior valves and fragments of some of the 

 median valves. The anterior valve is nearly semicircular, and the frontal 

 margin is only slightly sinuate. The tail-valve is exposed from the in- 

 terior and shows well the absence of the posterior sinus. The median 

 valve figured is from the Pine Creek limestone at Stoops Ferry, and the 

 illustration shows its short, wide form and the granulose surface. A 

 specimen showing the anterior and two median valves was found in the 

 Ames at the Brilliant cut-off, Pittsburgh, but the plates are not in their 

 natural position. 



This species can not be referred to Grypliochiton because the posterior 

 margin of the tail-valve is depressed instead of strongly sinuate, and it 

 differs from Pterochiton in not having the valves laterally excavated and 

 in having the frontal margin of the anterior valve only slightly sinuate. 

 The generic name here proposed is in allusion to the smooth curve of the 

 margin of the tail-valve. 



Glaphurochiton simplex sp. nov. 

 Plate XXIV, figures 11, 12, Plate XXVIII, figure 14. 

 Anterior valve unknown. Median valves represented by a single valve 

 which is short and somewhat rectangular in outline, a little wider than long. 

 Apex acute, lapping the valve behind. The jugal ridge is narrow, and the 

 sides slope abruptly. The sutural lamina* are short and wide. The 

 surface is marked by strong lines of growth and very fine granulations. 



