EARLY DEVONIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA l6l 



limestone and M. schoharie of the Schoharie grit though always 

 smaller. It is depressed at the umbo with the beaks obscure or suppressed, 

 has a broad and low umbonal ridge with a shallow and broad depression 

 or sinus in front of it. The hinge line is relatively short and straight ; the 

 posterior curve broadly explanate ; the lower margin contracting in front of 

 the middle and rounding to a narrow anterior margin. The general ex- 

 pression of the valves is that of broadly convex and explanate posterior 

 surface. Surface markings, sharp concentric striae. 



Goniophora mediocris Billings 



Plate 22, figures 6-8 



Goniophora mediocris Billings. Palaeozoic Fossils. 1874. v. 2, pt i, p. 50, 

 fig. 21 



Original description. Length of the cast of the interior about two inches; greatest 

 hight (near the mid-length), one inch; base gently convex with an obscure sinus a little in 

 front of the middle; hinge slightly ascending backwards, to a point just behind the mid- 

 length. From this point the posterior margin descends, with a straight or gently concave 

 slope, to the posterior angle, which is situated at about one third the whole hight of the 

 shell. Beaks small, closely incurved, almost in contact with each other, at about one 

 half the hight of the shell; below them the anterior extremity projects two or three lines. 

 From the beak a strong sigmoid angulation extends to the posterior angle. The surface 

 above this is gently concave, and below gently convex. A broad, shallow, barely per- 

 ceptible depression extends from the beak to the ventral margin, which it reaches just 

 behind the middle. Greatest depth of the valve a little in front of the middle. Depth of 

 both valves at this point (in a specimen about two inches long) one inch. 



Localitx and formation. Gaspe: Gaspe limestone, no. 8. 



This is a rare species and we figure the only example we have seen. 

 Locality. Lehuquets Cove, Forillon. 



Goniophora tethys (Billings) 



Plate 22, figures 14-16 



Sanguinolites tethys Billings, op. cit. p. 50, pi. 4, fig. 5, 5a 



Original description. Elongate; dorsal and ventral margins subparallel; anterior 

 extremity rounded, most extended at about one third the hight; posterior extremity 

 obliquely truncated; beaks at about one seventh the length of the shell from the anterior 

 ends, closely appressed; a strong obtusely rounded convexity extends from the beaks to 

 the ventral posterior angle. Length, three and one half inches; hight, about fifteen lines; 

 depth of both valves, nine lines. 



Only one specimen, an internal cast, of this species has been collected. The ventral 

 margin is imperfect, but it appears to have been gently convex, with a slight sinuation just 

 anterior to the mid-length. The hinge line is straight and two thirds the length of the 

 shell, slightly elevated posteriorly. The slope of the posterior margin occupies about one 

 third of the whole length. The posterior ventral angle, narrowly rounded or subacute. 

 Above the diagonal convexity, which extends from the beak to the lower posterior angle, 

 the sides are compressed or slightly concave. Below it they are gently convex, with a 

 broad shallow concavity from the beak to the ventral margin. 



