SOME NEW DEVONIC FOSSILS 213 



long posterior ridgelike tooth. These valves are very oblique, the 

 straight hinge making the greatest diameter of the shell ; the ante- 

 rior wing is insignificant and the posterior not extended. From 



Pteronitella peninsulae 



anterior and posterior cardinal angles the lateral margins depart at 

 almost 90 degrees. The beak is very near the anterior extremity 

 and the shell is quite convex along the oblique and somewhat 

 curved crescence line, from which the anterior slope is abrupt and 

 the posterior abrupt and slightly concave at first becoming flat at 

 the hinge. The anterior scar is small and deep, the posterior large 

 and faint. Beneath the beak are three or four teeth diverging from 

 the edge of the ligament area. 



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



Myalina pterinaeoides nov. 



One of the commoner species at Presque Isle stream is a Myalina 

 with a striking resemblance throughout, save in the character of 

 the hinge, to certain Pterineas with curtailed posterior wing, and 

 specially similar to Pt. f o 1 1 m a n n i Freeh. 1 



The frequent internal casts show the species to be devoid of 

 the hinge teeth of Pterinea and present only the moderately broad 

 ligamental striations of Myalina and the abbreviated earless and 

 abrupt front margin. This latter feature is rather feebly de- 

 veloped but when the shell is retained • the anterior incurvature 



x Frech. op. cit. pi. 10, fig. 5: Drevermann. Fauna d. Untercoblenzsch, p. 82, pi. 10, fig. 

 it 2. 



