406 
PROCEEDINGS OF THE ACADEMY OF 
Spirifera medialis (?) Hall.—Rep. IVtli Dist. N. Y., p. 208, fig. 8 ; 10th 
Rep. N. Y. Reg., p. 164. 
Locality. —Light-house, Ft, aux Barques, with S. Huronensis. 
Spirifera 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 
side 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, coarse, 
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, aud *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 
striae. Dorsal valve with a low rounded fold, marked (in the cast) by a sin¬ 
gle small median groove ; beak prominent, incurved over a small area. 
Locality. —Light-house, Pt. aux Barques, with Rhynchonella Huronensis , 
Sperifera Huronensis , Spc. 
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 Spiriferas. 
Retzia, King. 
Retzia polypleura, n. sp.—Shell of medium size or rather large, cuneate- 
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 depres&ed'hentral 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. 
