SOME NEW DEVON IC FOSSILS 205 



like the species cited in all respects so far as the former is known. 

 It is, however, possible that some of the coarsely ribbed internal 

 casts may belong to the more finely marked form to which we refer 

 in the following. 



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



Pterinea fasciculata Goldfuss 

 var. occidentalis nov. 



See Pterinea fasciculata Goldfuss. Petrefacta German iae, 2 : 

 137, pi. 129, fig. 5, and Freeh. Devon. Aviculiden Deutschlands. 

 1891. p. 84, pi. 8, fig. 1; pi. 9, fig. 1-3. 



This extremely common shell is essentially a miniature of 

 P. fasciculata Goldfuss. Though reduced in all its propor- 

 tions and in the strength of its ornament yet it expresses excellently 

 the characters of the German species. The valves are both 

 convex, the left notably and the right but slightly. The left 

 valve has the body well elevated above the posterior wing. 

 This wing is sometimes more incurved at the margin and more 

 extended at the point than in the figured German specimens 

 but these features are variable in the Dalhousie shells. The body 

 of the shell or direction of the crescence line is commonly more 

 oblique than in European specimens but this is an expression due 

 in some measure to mode of preservation, for examples occur here 

 quite as erect as those referred to. The breadth of the byssal groove 

 and emargination on the valve are also notable ; together with the 

 relative development of the anterior ear they are in full agreement 

 with P. fasciculata. The surface of this valve is marked by 

 coarsely fasciculated radial striae. Trie major ribs do not exceed 

 five or six but these are widely separated on the body of the shell, 

 the interspaces occupied by radii of lower order. 



On the posterior slope the striae are of uniform size and are 

 visible on the wing. On the anterior wing there are two or three 

 coarse riblets but the byssal sinus is deep and without radii. 

 Crossing these elevated radial lines are fine crowded and elevated 

 concentric lines giving all the surface except the byssal sinus a 

 reticulate ornament. 



The right valve is much less convex than the left, the anterior 

 wing relatively large, the byssal sinus deep, the body of the shell 



