4 
gaping, equivalve, hinge lateral pli- 
cate on one valve, angular on the oth- 
er. 1. O, bifid^H'ixL Shell bifid bj 
valves acute and gaping before, out- 
side black and rough, sides straight, 
length 3-8 of the breadth, hardly 
one inch. Knobhills. 
37. Terebrcitulites Eriensis , Raf. 
1818. Base smooth, remainder with 
concentric wrinkles, large valve with 
a depression and sinus. Length 4-5, 
thickness 2-5 df the breadth. From 
the limestone of Lake Erie and Ohio, 
silicified blackish, about one inch. 
38. STROPHOMENES, Raf. 
1820. See tract of October. l.Str. 
levigata. Very smooth, longer valve 
convex, lower valve concave, corners 
acute, not auriculate, contour arch- 
ed and even. Length 4-5 of the 
breadth. Kentucky limestone. 2. 
Sir . jlexilis . Very thin, lower 
valve hardly concave with minute 
curved strias, upper valve convex 
with minute flexuose strias, corners 
acute subauriculate, length and 
breadth equal. Limestone of Ohio, 
1 or 2 inches. 
40. CUIlVULITES, Raf. 1819. 
Inequilateral,! inequivalve, valves 
elongated, curved or crooked, larger 
valve broader, the smaller often an- 
gular. 1 . C. striata, Raf. 1818. 
Cuneate curved, base narrow, end 
broad rounded, striated longitudi- 
nally, short alternate strias near the 
end. In the Kentucky limestone, 
2| inches. 
41. ZONARITES, Raf. Tribe 
of Atremosia or imperforated Te- 
rebratulites. Shell substransversa! 
equilateral, subinequivalve, both 
valves convex with thick concentric 
wrinkles, hinge linear, beaks very 
small. 1 . Z. atrata. Nearly round- 
ed, with large wrinkles and furrows 
between. Length 5-6 of the breadth, 
thickness nearly half. Perfect black 
shell silicified, nearly one inch, from 
the Knobhills, disc, in 1822. 
42. Zoncirytes ? Tesselata , Raf. 
Rounded, tesselated by concentric 
and longitudinal wrinkles and fur- 
rows. Length 7-8 of the breadth. 
From the Knobhills, one inch broad, 
has only 1 valve incrusted in quartz, 
and with the hinge too imperfect to 
refer it decidedly to this Genus. 
VIII. ENCRINITES. 
This fossil tribe answers to the 
stellated animals, of which the As- 
terites are lacking with us, and the 
Echinites very rare; the true En- 
crinites differ from them by having 
a stem. We have a multitude of 
Genera and sp. My Pent remites of 
1817, my Tulosites described last 
month, &c. 
43. Stylcisirites. Stem articulated 
cylindrical, segments radiate or 5 lo- 
bed in the centre. 1 . St. flexistria , 
Raf. 1818. Segments equal, flat with 
flexuose strias around the central ra- 
diation. 2 . St. cliff or di. Segments 
equal fiat, radiation 5 lobed very 
large, centre with a round hole, 
border striated, both from Alabama 
as nearly ajl the following. 
45. Entrochites . Differ from 
last, centre of segments with a 
round hole and no rays. 1. E. ba- 
cillciria , Raf. 1818. Segnents con- 
nected in the shape of a barrel, une- 
qual, those in the middle thicker, 
each with a large hole and the bor- 
der striated. 2. E , concentrica . Seg- 
ments equafflat thin with concentric 
strias around the central hol&. 3. E . 
annulata . Segments equal, thick 
with a raised ring outside in the 
middle, hole large, no strias on the 
border. 
48. MESTYRITES, Raf. Differ 
from Stylastrites by centre cruciate 
or 4 lobed. 1. JR. cmmZata. Seg- 
ments equal thin, crenulate outside, 
border striate inside. 
49. STERAUL1TES, Raf. Dif- 
fer from Entrochites by segments 
solid, no hole in the centre. 1. St. 
gonites, Raf. Segments equal flat, 
outside with a circular angle in the 
middle, inside smooth. Alabama. 
50. Pentacrinites. Differ from Sty- 
lastrites by stem pentagonal out- 
side. 1. JP. quirtquejida, Raf. 1818. 
Segments quinquifid, convex below, 
above concave with a pentagonal 
hole and 5 ribs, alternate with the 
outward angles. Alabama. 
51. PENTAGONITES,Raf. Dif- 
fer from Entrochites by stem pen- 
tagonal. 1. P. crenularis . Seg- 
ments equal flat crenulate outside, 
borders striate inside. Alabama. 
52. FURCARITES, Raf. Head 
