NO. 1985. NEW SPECIES OF SILURIAN FOSSILS— WILLIAMS. 345 



and, approximately, 13 mm. across at end of sulcus (the edge is 

 broken in that specimen). Only a single sulcus is seen on the left 

 valve. Specimens figured as fig. 1 and 3 are probably distorted ex- 

 amples of this species. 



Formation and locality. — Upper part of the Pembroke formation 

 (Hersey red shale member) in Pembroke village at the three localities 

 numbered 2.32.9A, 2.42.8A, and 2.52.3A. 



Holotype.—Csit. No. 58968, U.S.N.M. (also M1303 and M1303.2). 



GRAMMYSIA TRIANGULATA (Salter). 

 Plate 31, fig. 17. 



1848. Orthonota triangulata Salter, Mem. Geol. Surv. Great Britain, vol. 2, pt. 1, 



Pal. append., p. 361, pi. 18, fig. 7. 

 1855. Grammysia cingulata var. triangulata Salter, M'Coy, Brit. Pal. Foss., p. 280, 



pi. \l, fig. 28. 



The figure we have given of a specimen from the Pembroke forma- 

 tion is very near both in form and size Salter's figure 7. 



Formation and locality. — Tough gray sandstone of the Pembroke 

 formation at the head of Long Cove, Pembroke Township (loc. No. 

 5.2.9A). 



Plesiotype.—Csit. No. 58970 U.S.N.M. 



Genus LEIOPTERIA Hall. 



LEIOPTERIA RUBRA, new species. 



Plate 31, fig. 4. 



This shell belongs to the same group of forms defined by Hall from 

 the Niagara under the names Avicula undata, A. subplana and 

 Posidonomya ? rTiomhoidea.^ Its characters are not sharply defined, 

 but in general form our species resembles A. undata Hall and differs 

 from that species in a more gibbous umbonal region the beak pro- 

 truding higher above the cardinal border, and the body more swollen, 

 and the shell is somewhat more extended along the umbonal ridge 

 making its form more elongate. 



The surface markings are a few concentric lines of growth otherwise 

 smooth. The posterior wing is well developed and submucronate. 

 The anterior ear is not in evidence. 



1 figure the specimen and give it a name as it is the only specimen 

 of the aviculoid type discovered in the Hersey red shale member of 

 the Pembroke formation. 



Formation and locality. — Hersey red shale member of the Pembroke 

 formation, at head of Giffs Bay Qoc. No. 2.32. 6A). 



Eolotype.—Ca,t. No. 58971, U.S.N.M. 



I Pal. New York, vol. 2, pi. 59. 



