SOME NEW DEVON IC FOSSILS 



197 



by a simple low rib, these interspaces being subdivided near the 

 margin. Concentric sublamellose lines at distant intervals. On 



Aviculopecten jumeaui 



the wing radial lines are obscure but concentric lines sharp and 

 crowded. 



Dimensions. The typical specimen has a length of 47 mm ; 

 hight of 42 mm. 



Lower Devonic. Perce rock, P. O. 



Aviculopecten ? incrassatus nov. 



Shell large, outline obliquely subelliptical. Posterior wing short. 

 Surface with coarse and heavy radial ribs of unequal size separ- 



Aviculopecten ? incrassatus 



ated by relatively narrow rounded grooves. Inequality in the size 

 of the ribs is noticeable in the umbonal region and new ribs are 



