138 



MOLLUSCA. 



Teeebratula. 



Deltoidal, gibbose; beak prominent; centre of tbe front 

 elevated, with three long plaits emanating near the beak ; 

 sides with four or more plaits below the middle. 



Carboniferous Limestone, Winster and Ardconnaught, 

 Ireland. 



81. Terebratula liATissiMA. — The Very Broad Terebra- 

 tula, pi. LVI. figs. 86, 87. 



T. lata. Sowerby, V. p. 165, pi. 502, fig. 1. 



Transversely elongated, convex ; larger valve the flattest, 

 with a produced beak ; front elevated ; surface -with forty regu- 

 lar divergent narrow ribs, ten or twelve of which are raised 

 with the front. 



Upper Greensand, Warminster and Devizes ; Lower Green- 

 sand, Athenfield and Parham. 



82. Terebratula depressa. — The Depressed Terebra- 

 tula, pi. LVI. figs. 9, 10. 



T. depressa. Sowerby, V. p. 165, pi. 502, fig. 2. 



Triangular, depressed ; front elevated, with about eight 

 plaits ; beaks produced ; lateral angles rounded ; whole surface 

 with about twenty regular divergent ribs. 



Upper Greensand, Isle of Wiglat and Blackdown, and Lower 

 Greensand, Pulborough. 



83. Terebratula nucipormis. — The Nut-Shaped Tere- 

 bratula, pi. LVa.* fig. 13. 



T. nuciformis. fc'owerby V. p. 1G6, pi. 502, fig. 3. 



Transversely elongated ; globoso ; front elevated ; beak pro- 

 duced ; surface with thirty rounded, regular, narrow, diver- 

 gent ribs, many of which have a slight groove near the front, 

 their edges plain and rounded. 



Upper Greensand, Rowde Hill, and Lower Greensand, 

 Shanklin and Pulborough. 



84. Terebratula acuta. — The Acute Terebratula, pi. 

 LVI. fig. 82, 83. 



T. acuta. Sowerby, II. p. 115, pi. 150, fig. 1, 2. Phillips, 

 Geo. York. I. p. 131, pi. 13, fig. 25. 



Triangular, a little transverse ; middle elevated, with one 

 very large acutely angular plait ; sides slightly rounded, with 

 one large and several small lateral plaits, on each seldom 

 exceeding two, the first largo and sharp, extending nearly to 

 the obtuse beak, the others merely undulations ; front sinus 

 almost an equilateral triangle. 



Inferior Oolite, Ilminster and Cheltenham, and the Lias, 

 Wilton Castle, and Bilsdale. 



85. Terebratula acuta-plicata. — The Acute-Plaited 

 Terebratula, pi. LV.* fig. 98, 99. 



T. acuta. Sowerby, V. p. 166, pi. 502, fig. 4. 



Transversely elongated ; somewhat pocket-shaped ; gibbose ; 

 beak a little produced, but small, and slightly curved ; front 

 elevated, with six plaits, the lateral ones being largest, the 

 wholo surface with many sharp plaits. 



Inferior Oolite, Bilsdale and Cheltenham. 



86. Terebratula plicatella. — The Folded Terebratula, 

 pi. LVI. fig. 08, 09. 



T. plicatella. Sowerby, V. pi. 503, fig. 1. 

 Elongated, somewhat quadrangular, inflated ; beak small, 

 incurved, with an ovate concave depression on each side under 

 it ; surface provided with about forty rounded plaits, some- 

 times furcated near the beaks, ten or twelve of which are 

 gradually elevate<l with the front ; sides descending in a rather 

 straight line from the urabones. 



Found very sparingly in the Inferior Oolite, Bridport. 



87. Terebratula serrata. — The Serrated Terebratula, 

 pi. LVI.* fig. 24, 25. 



T. serrata. Sowerby, V. p. 108, pi. 503, fig. 2. 



Suborbicular, subtriangular, inflated, with an obtuse margin ; 

 beak small, incurved, with a large, concave, ovate space on 

 each side beneath it ; surface with about eleven sharp plaits, of 

 which five are somewhat elevated in front. 



Lias, Lyme Regis. 



88. Terebratula truncata. — The Truncated Terebra- 

 tula, pi. LVI. fig. 20, 21. 



T. truncata. Sowerby, VI. p. 71, pi. 531, fig. 3. 



Slightly ovate ; hinge line nearly straight, and extending 

 the whole width of the valves ; larger valve subconical, with a 

 large, short, straight beak, flattened in front, and provided with 

 an ample round aperature ; surface with about twenty sharp, 

 sometimes furcated plaits ; front with from two to five ele- 

 vated ones ; lesser valve much flattened. 



Lower Greensand, Farringdon. 



89. Terebratula mantelliana. — Mantell's Terebratula, 

 pi. LVI. fig. 53, 54. 



T. Mantelliana. Sowerby, VI. p. 72, pi. 537, fig. 5. 



Transversely obovate, and inflated, with a small produced 

 slightly incurved beak ; with about sixteen large, sharp, simple 

 plaits, from four to six of which are considerably elevated infront. 



Chalk Marl, Ilamsey. 



90. Terebratula Gibbsiana. — Gibb's Terebratula, 

 pi. LVI. fig. 06, 07. 



T. Gilhsiana. Sowerby, VI. p. 72, pi. 537, fig. 4. 



Suborbicular, somewhat triangular, and inflated ; beak small, 

 acute, and incurved; lesser valve more convex than the other; 

 surface with numerous rounded simple plaits ; front greatly 

 elevated, with about ten or twelve flattened plaits. 



Lower Greensand, Folkstone, Sandgate, Boughton, and Isle 

 of Wight. 



91. Terebratula inconstans. — The Inconstant Terebra- 

 tula, pi. LVI. fig. 11, 12, 13. 



T. inconstans. Sowerby, III. p. 137, pi. 277, fig. 3, 4. 



Phillips, Geo. York. I. p. 94, pi. 2, fig. 24. 



Globular, beak small, acute, and incurved ; one-lialf of the 

 margin turned up and the other down, but sometimes in the 

 right, and at others the left ; a medial depression in the larger 

 valve ; surface with from twenty-four to twenty-six angular 

 plaits, half of them on one side elevated. 



Speeton Clay, Speeton and Knapton, and the Oxford Clay, 

 Heddington and Osmington. 



92. Terebratula obliqua. — The Oblique Terebratula, 

 pi. LVI.* fig. 8. 



T. oUiqua. Sowerby, III. p. 137, pi. 277, fig. 2. 



Subcompressed and transversely obovate ; beak produced and 

 slightly incurved ; surface with about fifteen angular plaits, 

 on one side five, central ones elevated, and turned downwards. 



Upper Chalk, Norwich and Ramsgate. 



93. Terebratula Manti^e. — Mant's Terebratula, pl.LVL* 

 fig. 13. 



T. Mantice. Sowerby. III. p. 137, pi. 277, fig- 1- 

 Subcompressed and subtrigonal, with the beak prominent 

 and slightly incurved, and forming nearly an equilateral tri- 

 angle ; front rounded ; surface with about sixteen angular 

 plaits, half of them on one side elevated ; upper valve convex. 



