350 Fossils of the Calciferous Sandrock. 



me to be the same species. If so, then the dorsal valve is convex, 

 and the species attains a much, larger size than that indicated 

 by the single valve in our possesion. The specimens range from 

 six lines to one inch in width, and are verv abundant. 



Locality and formation. — Mingan Islands,Calciferous Sandrock. 



Collector. — Sir W. E. Logan. 



LAMELLIBRANCHIATA. 

 CONOCARDIUM BlUMENBACHII. (N. S.) 



Description. — Triangular, ventricose, sub-cordiform, umbones 

 prominent incurved, the posterior or truncated extremity flattish 

 or gently convex with an oval outline, the greatest width being 

 at about one third the length from the beak ; the length from the 

 beaks to the posterior ventral margin in the best preserved spe- 

 cimen is sixteen lines, greatest width thirteen lines. On a side 

 view the form is sub-triangular, the posterior angle rather sharp, 

 about 80° j the ventral margin rounded ; the posterior edge or 

 ridge which runs from the beak to the posterior ventral angle is 

 nearly straight or but slightly convex in the lower half and thence 

 becomes more and more strongly curved until it reaches the beak. 

 The anterior side is a little longer than the ventral margin and 

 appears to have been nearly straight. Surface with rather strong 

 radiating ridges four or five in the width of two lines at the ventral 

 edge. 



The cast of the interior of the rio-ht valve indicates six or seven 

 crenulations on the posterior edge of the shell in the length of 

 two lines. 



The siphonal tube is not preserved in any of the specimens but 

 there are indications of its existence. There is a small species of 

 this genus in the Black River limestone but this is the first that 

 has been discovered in strata of such great antiquity as the Cal- 

 ciferous sandrock. 



Locality and formation. — Mingan Islands, White Limestone. 



Collectors. — Sir W. E. Logan, J. Richardson. 



GASTEROPODA. 

 HOLOPEA TURGIDA, (Hall, Sp.) 



Pleurotomaria ? turqida, Hall, Paleont. N. Y., Vol. 1, 



p. 12, Plate 3, Fig. 9, 10. 



Several specimens have been collected in the Calciferous Sand- 

 rock, Mingan Island, which appear to be of this species. 

 Collectors. — Sir W. E. Logan, J. Richardson. 



