Terebratula. 
MOLLUSCA. 
]37 
In the immature stato the elevation in front is hardly per¬ 
ceptible. 
Chalk Marl, Ilamsey. 
70. Terebratula pentagona,— The Pentagonal Tere¬ 
bratula, pi. LYL fig. 33, 34. 
T. pentagona. Sowerby, Sil. Syst. p. 0)2, pi. 5, fig. 22. 
Pentagonal, depressed; its width exceeding its length ; 
beak very small; obscurely trilobate ; with about twenty-five 
rounded plaits, but not extending to the beaks; the nine or 
ten central ones elevated at the base. Length six lines ; breadth 
six and a-lmlf lines. 
Upper Ludlow Rock, Delbury, Salop. 
71. Terebratula oblong a. —The Oblong Terebratula, 
pi. LV.* fig. .53, 54. 
T. oblonga. Sowerby, VI. p. 08, pi. 535, fig. 4, 5, 0. 
Oblong, gibbose; beak large, broad, and slightly curved, its 
length once and a-half its width, with sixteen or more forked 
plaits, with their edges rounded; hinge lino broad; front 
even. 
Lower Greensand, Ilythe, Lockswoll, and Farringdon. 
72. Terebratula orbicularis. —The Orbicular Terebra¬ 
tula, pi. LV.* fig. 58, 59. 
T. orbicularis. Sowerby, VI. p. 08, pi. 535, fig. 3. 
Uniformly convex; lesser valve orbicular, the larger with a 
large incurved boak ; surface minutely punctated with about 
fifteen angular simple plaits; but sometimes furcated near 
their commencement. 
Lias, Weston, near Bath. 
73. Terebratula angulata.— The Cornered Terebratula, 
pi. LV.* fig. 48. 
T. excavala. Phillips, II. p. 223, pi. 12, fig. 24. Anomia 
angulata. Linn. Syst. p. 1154. 
Oblong, compressed; beak small, incurved; surface with 
seven or eight very large angular flat-sided plaits, and deep 
furrows; somewhat excavated on their sides near the beak; 
base deeply indented. * 
Carboniferous Limestone, Cork, Dublin, and Isle of Man. 
74. Terebratula Martini. —Martin's Terebratula, pi. 
LV.* fig. 79, 80. 
T. Martini . Mantell, Geo. Sus. p. 131. T. pisum . 
Sowerby, VI. p. 70, pi. 536, fig. 6, 7- 
Suborbicular; somewhat quadrangular, thick and com¬ 
pressed ; beak small, incurved ; surface frequently granulated 
with numerous simple plaits ; base slightly elevated. 
Chalk Marl, Ilamsey and Folkstone, and the Under Green¬ 
sand, Isle of Wight and Blackdown. 
75. Terebratula flabellulum. —The Fan Terebratula, 
pi. LV/ fig. 63, 64. 
T. flabellula. Sowerby, VI. p. 67, ph 535, fig. 1. 
Depressed ; beak straight, rectangular, and projecting; 
lesser valvo transversely obovate; surface with about sixteen 
simple rounded plaits. 
Great Oolite, Ancliff, Wiltshire. 
76. Terebratula pugnus. —The Fist-like Terebratula, 
pi. LV. fig. 49. 
T. pugnus. Sowerby, V. p. 155, pi. 497. Phillips, Geo. 
York. II. p. 223, pi. 12, fig. 17. Ib. Pal. Foss. p. 87, pi. 35, 
fig. 156. Conch. Anomites pugnus ; Martin, Pet. Dcrb. pi. 
22, fig. 4,5. Airy pa pugnus ; Sowerby, Geo. Tran. 2d Ser. V. 
pi. 56, fig. 15, 18. 
Obovate-deltoidal, somewhat compressed ; beaks very short 
and nearly straight; sides of the valves convex, with several 
plaits on their edges, from whence a few furrows emanate, and 
extend a considerable way into the shell, nearly reaching the 
beaks in some instances ; base considerably elevated, with from 
four to six short rather obtuse plaits in the middle of the sinus; 
surface striated, but hardly visible to the naked eye. 
Carboniferous Limestone, Lolland, Derbyshire, Ireland. 
Devonian Series, Plymouth. 
This species is liable to great variety. 
77. Terebratula acuminata. —The Acuminated Tere¬ 
bratula, pi. LV.* fig. 66 to 74. 
T. acuminata. Sowerby, IV. p. 23, pi. 324, fig. 1. Phillips, 
Geo. York. IT. p. 222, pi. 12, fig. 4 to 9. lb. Pal. Foss. p. 88, 
pi. 35, fig. 159. 
Heart-shaped, gibbose; beaks very small; one valve with 
a deep and wide central sinus, nearly dividing it into two 
lobes, the other elevated ; surface with numerous nearly obso¬ 
lete divergent strim. 
Carboniferous Limestone, Yorkshire, Derbyshire, and Cork, 
Ireland. 
This species is so variable, that no single specific character will apply 
to these. It also varies considerably in its progress from the young to 
the adult condition. Professor Phillips arranges them thus :— 
Variety 1.—Front angular, a. No mesial plaiis; with or without 
lateral plaits, fig. 66, 67, 68 ; the young, fig. 72. 
b. Mesial plaits variable ; with or without lateral plaits; 
whole surface sharply pointed. 
Variety 2. — Front arched, with mesial plaits, fig. 69 ; young of the 
same, 70, 7 k 73. 
Variety Plicato , fig. 74. — With from three to five plaits; from 
Ireland and near Clitheroe. 
Variety Sulcata, fig. 67.-—From the Carboniferous Limestones, 
Clitheroe, Lancashire. 
78. Terebratula tetrahedra. —The Four-sided Terebra¬ 
tula, ph LV* fig. 85, and pi. VI. fig. 45, 46. 
Terebratula tetrahedra. Sowerby, I. p. 191, ph 83, fig. 4, 
and T. media , fig. 5, Liet. Pet. ph 41, fig. 1. 
Obtusely deltoidal, gibbose ; general form a tetracdon, with 
rounded edges ; beaks a little incurved ; front with a central 
elevation, provided with four or five sharp plaits on each side, 
which emanate from the beak, and terminate on the sides; 
the distance between the lateral and central plaits about three- 
fourths the length of the valves. 
The variety T. media , fig. 83, is more rounded, and the plaits 
six in number. 
Kelloway's Rock, Kelloway ; Oxford Clay, Wheatley ; the 
Fuller's Earth, Aynhoe and Banbury; Inferior Oolite, So¬ 
mersetshire and Hebrides ; and the Lias, Yorkshire. 
79. Terebratula cordifoiimis. —The Heart-shaped Tere¬ 
bratula, ph LV/ fig. 92, 93, 94. 
T. cordiformis . Sowerby, V. p. 154, fig. 2, 4. 
Heart-shaped ; front greatly elevated, with a deep marginal 
sinus; sides rather convex, with sharp edges; centre with 
threo or more acute angular furrows, emanating near the beaks 
and reaching to the base ; exceedingly variable in size. 
Carboniferous Limestone, Cork and Connaught, Ireland. 
80. Terebratula crumena. —The Pocket-shaped Tere¬ 
bratula, ph LV.* fig. 96, 97. 
T. crumena. Sowerby, I. p. 190, fig. 2, 2*, and 3. 
Anomites crumena . Martyn. Pet. Derbs. ph 36, fig. 4. 
2 M 
