IIO NEW YORK STATE MUSEUM 



anterior row begin abruptly beneath the beak and are coarse and oblique, 

 4 to 5 in number. 



Localities. Abundant at Presque Isle stream and in the Burnt land 

 westward. 



Palaeoneilo mainensis Clarke 



Plate 28, figures 24-30 



Palaeoneilo mainensis Clarke. N. Y. State Mus. Bui. 107. 1907. p. 230 



Shell attaining large dimensions for a species of the genus, subtrihe- 

 dral, depressed convex, with beak but little in front of middle of the hinge. 

 Might three fifths of the length. Posterior surface gently sinuate and the 

 postlateral shell margins correspondingly emarginate, extremities narrow. 

 Surface covered with fine concentric growth lines. On the interior the 

 muscle scars are deeply impressed, there being a ridge on the umbonal side 

 of each but both anterior scar and ridge are very much the more strongly 

 marked and almost attain the strength of the ridge in Nuculites. The 

 hinge has the following structure : The posterior arm carries a row of 16 to 

 1 8 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. orb igny 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 agree- 

 ment in critical details. We may observe, however, that the shell occasion- 

 ally 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. maureri Beushausen and some of its variants 

 in the Coblentzian fauna. [Beush. op cit. p.8s, pi. /, fig. 11-28] 



Localities. Abundant at Presque Isle stream and 2 miles westward in 

 the Burnt district. 



Palaeoneilo circulus Clarke 



Plate 28, figures 13-14 



Palaeoneilo circulus Clarke. N. Y. State Mus. Bui. 107. 1907. 1x231 



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

 evenly convex, with beak somewhat anterior, surface marked by the fine ele- 

 vated concentric lines characterizing so many species of this genus and with 

 a very low posterior sulcus. Muscle scars slightly buttressed by shelly ridges. 



Locality. Presque Isle stream. 



