205 



twelfth of the length of the valve. The central group of muscle scars is 

 rather large and lies at the bottom of the deep cavity of the valve ; the 

 anterior laterals (j) are a little more than a third from the front of the 

 valve. Distinct impressions of vascular trunks may be seen on each side 

 toward the margin of the valves. 



Sculpture. The outer surface appears dull and without lustre, but in 

 proportion to the size of the shell, it is coarsely granulated, and towards 

 the margins has indistinct ridges parallel thereto. 



Size. Length of the ventral 5 mm. ; width 4 mm. The dorsal is 

 mm. shorter. 



Horizon and locality. Collected by M. A. H. Foord on the Mira river 

 in 1874. The special locality is not given, but the matrix is a fine mica- 

 ceous sandstone like the flags of Div. C. 2 c. 



The resembling form mentioned above as occurring in the St. John Compared to 

 flags at Courtney bay is somewhat smaller but has a similar radular 

 ornamentation. 



This species is nearly as large as that described by Mr. Walcott as 

 (L) bellulus from Kellys island, Conception bay, Newfoundland.* 



This latter species is the same as that described by Dr. Whiteaves 

 many years ago from that locality under the name of Lingula ' Billings- 

 ana. I have co-types of this species and of L. bellulus, butl do not find 

 on the Cape Breton species described above the fine irregular striae 

 said to be characteristic of the latter. It is also a comparatively wider 

 species. 



WESTONIA, subgen. Walcott. 



" Ovate with ventral valve slightly accuminate ; area of ventral valve Sub-genus 



, . , o Westonia of 



strongly defined, and divided by a relatively large pedicle groove, bur- Wa i cott . 



face marked by concentric and radiating strise that are crossed by trans- 

 verse semi-imbricating ripple-embossed lines. As far as known, the muscle 

 scars and vascular markings are essentially the same as in Obolus." 



Mr. Walcott takes for the type of this subgenus 0. aurora of the St. 

 Croix sandstone (upper part) and with this, his diagnosis agrees. And he 

 includes Lingulella (?) lens of the Cape Breton fauna, with which the 

 description of the subgenus does not agree in several respects, e.g. the 

 ventral valve is not acuminate but is bluntly pointed, the area though 

 well defined, is not high, being about one seventh of the length ; and 



*Proc. U.S. Nat. Mus. vol. xxi, p. 398 (no figure). Am. Jour. Sci. 3 Ser. xvi, 78, p. 

 226. 



