19 



The dorsal valve has not been seen. 



The surface is covered with fine sub-angular radiating striae which, 

 increase by fission and intercalation. Of these there are from seven to nine 

 in the width of one line. There is also a set of minute concentric striae, 

 between thirty and forty in the width of one line. 



The following are the dimensions of several specimens in Hnes, the first 

 number indicating the width on the hinge line, and the second the length. 

 16-12, 12-8, 10-6, 11-7, 12-8, 14-10. 



This species differs from all others of the genus, yet discovered in 

 Canada, by having the ventral valve concave instead of convex. 



Locality and Formation. — In the Gaspe sandstone at Gaspe, and in 

 the limestone at Split Rock, Perc^. Lower Devonian. 



Collectors, — First discovered by Dr. J. W. Dawson, at Gaspe. After- 

 wards found by Thos. Curry at Perce. Lower Devonian. 



Chonetes Antiopa, (N. sp) 



Decsription. — Shell small, semi-elliptical ; cardinal angles about 90^ ; 

 sides nearly straight in the posterior third or half of the length, 

 anterior angles uniformly rounded ; front inargin broadly or gently con- 

 vex ; width about one-fourth or one-half greater than the length. Ventral 

 valve moderately and sometimes rather strongly convex, most elevated 

 about the mid-length ; somewhat compressed at the angles ; umbo usually 

 slightly elevated. Often the shsU is more or less abruptly inflected about 

 the mid-length, with a flattened or only gently convex slope to the 

 front margin. Sometimes there is a shallow groove, which extends from 

 the beak along the median line to the front. There are two spines on 

 each side of the beak, slightly sloping outwards, nearly erect, sometimes 

 gently curved, the convex side of the curve outwards. There may be 

 a third spine at the cardinal angle, but it has not yet been observed. 



The surface to the naked eye appears nearly smooth, but, when magni- 

 fied, exhibits about fifteen rounded, sub-angular striae in the width of one 

 line. 



Width four or five lines. Although a large number of specimens have 

 been collected, none of them exhibit the area or the dorsal valve. 



This species is about the size of C. lineata, Vanuxem, as figured in th: 

 Pal. N. Y., vol. 4, but is proportionally somewhat broader, not so con 

 vex, and has larger spines. 



Locality and Formation. — In the limestone at Mount Jolli and in the 

 Split Rock at Perc^. Lower Devonian. 

 Collector. — Sir \Y. E. Logan. 



