86 NEW YORK STATE MUSEUM 



Chonetes nectus Clarke 



Plate 20, figures 22-25 



Chonetes nectus Clarke. N- Y. State Mus. Bui. 107. 1907. p.z63 



A small coarse ribbed species, transversely elongate in form and having 

 14 to 1 6 striae, each of the larger of which is divided at variable distances 

 from the middle to the margin of the valve. It is but slightly convex com- 

 pared with C . hudsonicus Clarke and does not attain a length of 

 more than 1 1 mm. A peculiar feature of the species is the general preva- 

 lence of a deep concentric constriction in the ventral valve which is present 

 in every such valve yet recognized. 



The interior of the dorsal valve is highly radio-pustulate, there being 

 two strong central diverging ribs traversing the valve. 



Localities. Misery stream, first dam in town of Sandwich ; Moose 

 river at Stony brook, Tomhegan point, Moosehead lake, Me. 



Chonetes (Eodevonaria) hudsonicus Clarke 



Plate 20, figures 26-28 

 Ste pt i, p. 238 



The specimens of this species are highly characteristic varying in out- 

 line as do those of the Gaspe sandstone (var. g a s p e n s i s), some long 

 and narrow, others broad, more nearly semicircular. In all, the singular 

 row of hinge denticulations is highly developed. 



Localities. Tomhegan point, Moosehead lake ; Moose river at Stony 

 brook. 



Chonetes canadensis Billings 



Plate 21, figures 1-4 

 See pt i, p. 205 



The expressions of this remarkable species here appearing, elsewhere 

 known only at Grande Greve and Perce, are in some respects extravagant. 

 They do not always attain the maximum of size presented by the Perce 

 examples but in them is carried to an extreme the development of the 

 median internal septal ridge on the dorsal valve, which now becomes a sharp 

 and elevated keel. The hinge sockets on this valve are greatly developed 

 and produced, while the vascular sinuses with their intervening ridges are 

 more pronounced than in any specimens we have elsewhere seen. The 

 exterior of the ventral valve carries the characteristic median rib. 



Locality. Misery stream, first dam in town of Sandwich. 



