406 rKOCEEDINGS OF THE ACADEMY OF 



Spikifera medialis (?) Hall. Rep. IVth Dist. N. Y., p. 208, fig. S ; lOtli 

 Rep. N. Y. Reg., p. 164. 

 Locality. Light-house, Pt, aux Barques, with S. Huronensis. 



Spikifera Huronensis, n. sp. Shell of medium size, transversely semi-el- 

 liptic, with acuminate hinge-extremities ; entire hinge-length nearly three times 

 the length of the shell ; anterior and antero-lateral borders regularly curved. 

 Ventral valve ventricose, especially towards the beak, which is erect over a 

 high, triangular area, triangularly foraminated to the apex ; sinus beginning 

 near the beak, not well defined, round at its margins and bottom ; entire sur- 

 face covered with about forty rounded ribs, of which the lateral half on each 

 hide terminate upon the cardinal border, while about four, of the same size as 

 their neighbors, occupy the sinus. Dental plates standing at an angle of 58. 

 Dorsal valve equally tumid with the ventral ; beak incurved over a narrow 

 area ; mesial fold indistinct, with three or four ribs ; occlusor and pedicle 

 scars lanceolate, deep. Surface of shell with one or two squamous incremen- 

 tal lines. 



Length of shell, -49 (100) ; length of hinge line 1-3 (265) ; convexity of ven- 

 tral valve -25 (50). 



Locality. Light-house Pt. aux Barques, in a hard, gray, pyritous, coar?e, 

 often conglomeritic bed of sandstone two feet thick, intercalated in the argilla- 

 ceous slates of the Huron group. 



Spirifera pharovicina, n. sp. Shell large and ventricose. Ventral valve 

 with a gentle sinuation which extends to the beak ; dental plates moderately 

 long, forming an angle of 80 ; area very elevated, with a narrow triangular 

 fissure reaching to the apex, which scarcely overhangs the area ; surface 

 faintly marked each side of the sinus by rather remote radiating ribs, which, 

 near the margin, are somewhat distinct. Some impressions of areas supposed 

 to belong to this species, are 2*1 long, and "95 high, with a fissure *44 wide at 

 base ; deltoidal impression grooved in the direction of the fissure ; surface of 

 area flat, slightly incurved at apex and marked by very distinct transverse 

 stride. Dorsal valve with a low rounded fold, marked (in the cast) by a sin- 

 trie small median groove ; beak prominent, incurved over a small area. 



Locality. Light-house, Pt. aux Barques, with Rhynchonella Huronensis. 

 Sperifera Huronensis, Sfc. 



This well marked species is known only by imperfect casts. 



Spirifera (?) insolita, n. sp. Shell large, smooth. Ventral valve with a 

 broad, concave sinus reaching to the beak, and forming at its lateral margins 

 angles with the shell surface ; area short and imperfectly bounded, though 

 the beak is rather high ; dental plates very long, reaching the middle of the 

 shell or beyond, and forming with each other an angle of 25 Q , which is the 

 same as the rostral angle of the mesial sinus. 



Locality. Light-house, Pt. aux Barques. 



This species has the short hinge line of Brachythyris, and the smooth 

 surface of Martinia characters which, with the very long and approximate 

 dental plates render it unique among Spiriferae. 



Retzia, King. 



Retzia polypleura, n. sp. Shell of medium size or rather large, cnneate- 

 oval, tumid. Ventral valve with a prolonged, isolated, nearly erect, perfor- 

 ate beak, which projects one-fourth the valve length beyond the dorsal valve, 

 a swollen umbo, and depressed central and anterior region. Dorsal valve ro- 

 tund, with a subcuneate rostral margin ; beak obtuse, closely appressed 

 against the ventral valve ; umbo ventricose ; entire valve with a regular car- 

 dium-like convexity ; median ridge extending one-third the length of the 

 valve, with a lanceolate occlusor impression on each side of it. Surface 

 marked by about forty small rounded radiating ribs. Spires not seen. 



[Sept. 



