346 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.45. 



Genus EURYMYELLA Williams. 



EURYMYELLA SHALERI var. MINOR Williams. 

 Plate 31, fig. 5. 



1912. Eurymyella shaleri var. minor Williams, Proc. U. S. Nat. Mus., vol. 42, 

 p. 387, pi. 49, fig. 9. 



This variety is occasionally seen in the Hersey red shale member 

 of the Pembroke formation, and does not seem to differ appreciably 

 from the common form of the Eastport formation. Specimens of the 

 typical species E. shaleri have not been seen in these lower beds. 



Foi^mation and locality. — Hersey red shale member of the Pembroke 

 formation, on the west shore of Sipps Bay, south of the highway 

 bridge (loc. No. 2.32.9A). 



Plesiotype.—Csit. No. 58972, U.S.N.M. 



Genus MODIOLOPSIS Hall. 

 MODIOLOPSIS LEIGHTONI, new species. 



Plate 31, figs. 7, 8, 9, 10. 



This species is very common in some layers of the Pembroke 

 formation, and shows considerable variation in form and size. The 

 specimens selected for illustration (figs. 7, 8, 9, 10) together express 

 fairly the general appearance of the shell. As the illustrations show 

 no two specimens are exactly alike. In the following definition are 

 noted the characters expressed bj^ average specimens. 



Shell transversely subovate; length a little more than twice the 

 height; hinge line nearly straight; posterior height slightly greater 

 than anterior. Beak within the anterior third of hinge length, low, 

 flattened, ovate, arching; the umbonal ridge strong, gradually flat- 

 tening out toward postero-ventral angle. Middle of shell flattened, 

 slightly depressed from over the beak to the front. Surface covered 

 by irregular lines of growth. 



Two specimens taken as expressing average size and dimensions 

 measure: Cat. No. M1351.35, length, 21; height at middle, 9^; at 

 beak, 9 mm. Cat. No. M1351.4, length, 22^; height at middle, 10; 

 at beak, 9 mm. 



The corresponding dimensions of Billings's figure of M. exilis from 

 the Arisaig (pi. 8, fig. 6) are 40 by 16 by 14, showing the difference in 

 size in comparison with a species perhaps more nearly related to this 

 one than any other American described species. 



Formation and locality. — Pembroke formation, in Leighton gray 

 shale member, at head of Leighton Cove, Pembroke Township (loc. 

 No. 5.3.8F and M). 



Cotypes.—Csit. No. 58974, U.S.N.M. 



