EARLY DEVONIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA 145 







genus Eodevonaria. In this little association are Chonetes billingsi 

 of the Grande Greve limestone and Gaspe sandstone, C . n e c t u s , Moose 

 River sandstone, C. laticosta Hall, C. mucronatus Hall and the 

 species under consideration. Chonetes laticosta Hall was described 

 from the Onondaga limestone and C. mucronatus from the Marcellus 

 shale. Hall united both terms under the latter in his redescription [Palae- 

 ontology of N. Y. 4 : 126] though still recognizing that the earlier examples 

 are more convex and more coarsely and sharply plicated than the later. It 

 seems quite likely that the apparent difference to typical C. laticosta 

 and C . mucronatus is permanent and always recognizable. C. h i g h- 

 1 a n d e n s i s , the species before us, is another shell of this small convex 

 coarse ribbed type quite distinctively characterized in the following respects : 

 The ventral valve is almost gibbous with a decided median elevation and 

 the surface carries 12-14 riblets which are coarse and well denned in early 

 growth but become obscure and obsolete on the anterior slopes of the valve. 

 This peculiar obsolescence of the ribs lends a special distinguishing feature 

 to the shell, to which may be added usual indications of interrupted periodic 

 growth. The casts of the exterior do not indicate the presence of the fine 

 concentric lines present in C. billingsi, C. laticosta and C. 

 mucronatus. So marked is the obsolescence of the riblets in late 

 growth that it is not clear whether they increase by normal bifurcation on 

 the valve except at some abrupt growth line. On the dorsal valve, how- 

 ever, where the ribs seem to be fewer, bifurcation is common. The hinge is 

 cornute and not denticulate. On the interior of the ventral valve is a short 

 but deep median septum at either side of which are broadly flabellate muscle 

 scars. On the dorsal the cardinal process is erect and divided ; the interior 

 surface bears granulated riblets, of which a median pair separated by a 

 single rib is most prominent, the aspect in this respect of the interior being 

 like that in C . billingsi. With other preservation the elevated muscle 

 scars are apparent. The average adult shell of this species has a width of 

 7 mm and a length of 6 mm. It is very abundant. 



Dalmanella planoconvexa Hall 

 Quite characteristic examples of this Helderbergian species are common. 



Dalmanella perelegans Hall ? 



See pt i, p. 61 



Probably the same as the Helderbergian species. 



There are in this fauna, so far as known, certain features already 

 referred to as present in that element of the Gaspe sandstone which have 

 seemed to the writer to distinctively mark a Middle Devonic (Hamilton) 

 age. In the presentation of the Gaspe sandstone fauna in part i of this 



