142 
CONCHIFERA. 
Terebratula. 
134. Terebratula crenulata. —The Crenulated Tere¬ 
bratula, pi. LVI. fig. 74, 75. 
T. crenulata. Phillips, Pal. Foss. p. 85, pi. 34, fig. 152. 
Pentagonal; beaks very obtuse and rounded, compressed; 
sides and base nearly parallel ; whole surface, except near the 
umbonal regions, covered with fine numerous deep furrows, 
with rather flat intermediate ribs. 
Devonian Shales, South Devon and Barton. 
135. Terebratula ventilabrum. —The Bellied Terebra¬ 
tula, pi. LVI. fig. 84, 85. 
T. ventilabrum . Phillips, II. p. 223, pi. 12, fig. 36, 38, 39. 
Rhomboideo-deltoidal; margins sharp, with obtuse ribs; 
upper valve sulcate near the beak, which is obtuse; sides 
nearly obliquely parallel, with five or six mesial ribs. 
Carboniferous Limestone, Bolland. 
136. Terebratula anisodonta. —The Unequal-notched 
Terebratula, pi. LVI. fig. 58, 59. 
T. anisodonta. Phillips, Pal. Foss. p. 86, pi. 34, fig. 154. 
Transversely oval, depressed; beak somewhat prominent; 
front straight, with a large angular elevation raised to a straight 
mesial edge, which is deeply indented by six narrow rounded 
ribs; sides rather reflected towards the deeper valve; broadly 
and deeply notched by short considerably elevated ridges. 
Devonian Shales, Barton, South Devonshire. 
137. Terebratula socialis. — The Social Terebratula. 
T. socialis. Phillips, I. p. 112, pi. 6, fig. 8. 
Transversely oblong-ovato ; beak short; mesial elevation 
with four prominent ribs ; sides slightly rounded; whole sur¬ 
face with very strong and rather acute ribs. 
Calcareous Grit, and Kelloway's Rock, Scarborough and 
Hackness. 
138. Terebratula spinosa. — The Spinous Terebratula, 
pi. LVI.* fig. 1. 
T. spinosa. Smith, p. 108 ; Knorr, Tet. Dil. 2 pi. B. 4, 
fig. 4. Phillips, Geo. York. I. p. 123, pi. 9, fig. 18. T.aspira. 
Kflnig, Icon, fig. 219. 
Subtriangular ; beaks rather obtuse ; sides gradually round¬ 
ed ; surface with rather broad longitudinal ribs, provided with 
obtuse, somewhat distant spines. 
Great Oolite Cave, and Bath, and the Inferior Oolite, 
Dundry ; Cheltenham, Bayeux, and Bole. 
139. Terebratula ambligonia. —The Obtuse-angled 
Terebratula, pi. LVI.* fig. 33. 
T. arnbligona. Phillips, Pal. Foss. p. 88, pi. 35, fig. 160. 
Pentrahedral, oblong, a little convex, with the surface 
slightly elevated ; umbones somewhat produced, from whence 
a mesial furrow proceeds, and terminates on the basal margin, 
on each side of which are five rather large and rounded diver¬ 
gent ribs ; mesial furrow on the deep valve bounded by two 
ribs, which are shorter than the others. 
Devonian Shales, South Devon, Barton, and Babbacombe. 
1 40. Terebratula sulcirostris. —The Furrowed-beaked 
Terebratula, pi. LVI/ fig. 9 and 12. 
T. sulcirostris. Phillips, Geo. York. II. p. 222, pi. 12, fig. 
31, 32. 
Rhomboideo-deltoidal; beaks slightly developed; central 
area with from five to nine pretty deep divergent furrows, 
with intermediate ribs, and producing a square projection on 
the base; ribs on the sides flat, and slightly defined; edge 
sharp ; upper valve with the furrows reaching the beak. 
This species is subject to two varieties, one of which liae numerous 
ribs, and the other with fewer. 
Carboniferous Limestone, Bolland. 
141. Terebratula laticosta. —The Broad-ribbed Tere¬ 
bratula, pi. LVI.* fig. 10, 11, 63, 64. 
T. laticosta . Phillips, Pal. Foss. p. 85, pi. 34, fig. 153. 
Transversely elliptical; beaks small, slightly produced, and 
angulated, with a very small perforation ; front provided with 
a mesial sinus; about twenty obtuse, almost equal, prominent 
ribs cover the surface; those are more enlarged towards the 
borders, which are obtuse, and crossed by distinct lines of 
growth. 
There are two varieties of this species. Fig. 63 and 64 are the ordi¬ 
nary form, and 10 and 11 the variety ; the former is from the Limestone 
at Boggy Point, North Devon, and the latter from Barton, North 
Devon. 
142. Terebratula lacunosa, pi. LVI.* fig. 15. 
T. lacunosa. Sowerby, Sil. Syst. p. 624, pi. 12, fig. 10. 
Transversely elliptical, with a projecting sinus; surface 
with numerous divergent rounded ribs, which project beyond 
the edges; larger valve with the beak considerably incurved, 
and both of them obtuse. 
"Wenlock Limestone, Wenlock Edge ; Nash Lime Scar, and 
Wallsall. 
Genus XIII. ORBICULA.— Cuvier. 
Shell inequivalve, nearly orbicular, compressed, generally 
irregular in form, adherent, flat, and attached by means of a 
fibrous substance passing through an orifice near the centre of 
the lower valve. ITpper valve patelliform, its vertex pos¬ 
terior or nearly central; each valve provided with four mus¬ 
cular impressions, two of which are largo, approximate, and 
situate near the ceutre ; two smaller and more distinct ones 
placed near the posterior margin; those of the lower valve 
not so well defined as the others; near the inner extremity of 
the orifice there is an obtuse testaceous process, destitute of 
hinge—teeth, or ligament. 
1. Orbicula punctata. —The Punctured Orbicula, pi. 
LVI.* fig. 54. 
O. punctata. Sowerby, Sil. Syst., p. 636, pi. 20, fig. 5. 
Lenticular, much compressed ; apex submarginal; surface 
with fine granulations, each of which is punctured. Diameter 
half an inch. 
Lower Silurian Rocks, Chatwall, Caradoc. 
2. Orbicula rugata. —The Rough Orbicula, pi. LVI.* 
fig. 57, 58. 
O. rugata. Sowerby, Sil. Syst., p. 608, pi. 4, fig. 47, 48, and 
p. 610, pi. 5, fig. 11. 
Almost orbicular; upper valve a much depressed cone, with 
the surface concentrically wrinkled; lower valve nearly flat. 
Diameter six lines, height two lines. 
Upper Ludlow Rock, Ludlow, Promontory, Richards Castle, 
and many other localities. 
3. Orbicula striata. —The Striated Orbicula, pi. LVI.* 
fig. 61, 62. 
O. striata. Sowerby, Sil. Syst., p. 610, pi. 5, fig. 12. 
Orbicular, very convex; apex deflected, marginal, covered 
with minute radiating stria?. Diameter seven lines, height 
three lines. 
Upper Ludlow Rock, Delburv and Ludlow Hills. 
