MUSEUM OF COMPARATIVE ZOOLOGY. 69 



Rhynconella anticostiensis Billings. New Species of Low. Sil. Fossils; 

 Can. Geoi. Sur., 1862, p. 142, Fig. 119. — English Head, Anticosti. 



Rhynconella glacialis Billings. New Species of Low. Sil. Fossils; Can. 

 Geol. Sur., 1862, p. 143, Fig. 120. — Ellis Bay, Anticosti. 



Brachymerus Sualer. 



Anterior (dorsal) valve the more convex. Dental lamellae serrate or 

 lobed on the outside. Septa of anterior valve with two broad, thin brachial 

 plates projecting from them near their junction with the hinge-line; ex- 

 terior surface plicated. 



A member of the same family as Pentamerus, to which it is very closely 

 allied. 



Type. — Pentamerus VcrneuiUi Hall. 



Brachymerus reversus Sualer. 



Syn\ Pentamerus reversus Billings ; Canada Geol. Survey, 1857, p. 

 295. — Junction Cliff, Anticosti. 



Pentamerus Sowerbt. 

 Pentamerus Barrandii Billings; Canada Geol. Survey, 1857, p. 296.— 

 Bocscie River Bay. 



Athyris McCoy. 

 Athyris turgida Sualer. 



Shell sub-circular ; transverse diameter equal to distance from beak to 

 border ; from valve to valve about four fifths the transverse diameter. 

 Toothed valve very convex ; most elevated at one third the distance from 

 beak to border ; umbo rising above the hinge-line for a distance equal to 

 one fifth the transverse diameter; closely incurved; beak indistinct; socket- 

 valve very convex ; most elevated point one third the distance from beak 

 to border; depth equal to one third of the diameter, about two thirds a? 

 great as that of opposite valve ; umbo rising above the hinge-line a distance 

 equal to one fifth the diameter of valve. Surface with numerous distinct 

 concentric lines of growth. Toothed valve with a narrow, shallow mesial 

 sinus, which produces a flattening for some distance from the border. 



From beak to border, seven lines; transverse diameter, seven lines; 

 valve to valve, five lines. — Ellis Bay, Anticosti. 



Athyris umbonata Billings. New Species of Low. Sil. Fossils; Canada 

 Geol. Survey, 1862, p. 144. — Junction Cliff, Anticosti. 



Athyris prinstana Billings. New Species of Low. Sil. Fossils ; Canada 

 Geol. Survey, 1862, p. 145. — Prinsta Bay. 



Athyris Julia Billings. New Species of Low. Sil. Fossils ; Canada Geo! 

 Survey, 1862, p. 146. — Jumper's Cliff, Anticosti. 



