SOME NEW DEVONIC FOSSILS 23I 



The hinge has the following structure: The posterior arm carries 

 a row of 16-18 ligament pits ending at the anterior edge of the 

 posterior adductor. Those directly under the beak are very slender 

 and transverse, outward they become stronger and more and more 

 chevron-shaped; the anterior arm is not separated by an oblique 

 line from the posterior and carries seven or eight pits, increasing 

 outward rapidly in size and becoming strong and oblique at the 

 terminus near the inner edge of the adductor. In respect to hinge 

 structure, the species is readily distinguishable from P. o r b i g n y i, 

 which it sometimes resembles in form. It is not easy to find 

 European or Mississippian species which this shell resembles in 

 form and hinge structure. Comparisons of similarity are readily 

 made with species of the Devonic on both sides of the Atlantic 

 but these are not helpful in the absence of agreement in critical 

 details. We may however observe that the shell occasionally puts 

 on a concentrically wrinkled surface which we find together with 

 agreements in outline, convexity and, so far as can be ascertained, 

 in hinge structure, expressed in P. m a u r e r i Beushausen and 

 some of its variants in the Coblentzian fauna. [Beush. op. cit. 

 p. 85, pi. 7, fig. 11-28] 



Lower Devonic. Abundant at Presque Isle stream and 2 miles 

 westward in the burnt district, Chapman Plantation, Me. 



Palaeoneilo circulus nov. 



Shell small, almost circular in outline, slightly oblique, depressed 

 and evenly convex, with beak somewhat anterior, surface marked 



Palaeoneilo circulus 



by the fine elevated concentric lines characterizing so many species 

 of this genus and with a very low posterior sulcus. Muscle scars 

 slightly buttressed by shelly ridges. 



Lower Devonic. Presque Isle stream, Chapman Plantation, Me. 



