Terebratula. 



MOLLUSCA. 



is: 



In tlie immature state the elevation in front is hardly per- 

 ceptible. 



Chalk JIarl, Ilamsey. 



70. Teuehratcla pentac;o.\a. — The Pentagonal Tere- 

 bratula, pi. LYI. fi^. 3.3, 34. 



T. ])cnla</ona. Sowcrbv, Sil. Syst. p. CI 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-half lines. 



Upper Ludlow Rock, Delbury, Salop. 



71. Tekebratula obloxga. — The Oblong Terebratula, 

 pi. LV.* fig. 53, 54. 



T. oblonga. Sowerbv, XI. p. GS, pi. 535, fig. 4, 5, C. 



Oblong, gibbose ; beak large, broad, and slightly curved, its 

 length once and a-half its w^idth, with sixteen or more forked 

 plaits, with their edges rounded ; hinge line broad ; front 

 even. 



Lower Greensand, Hythe, Lockswell, and Farringdon. 



72. Terebratula orbicularis. — The Orbicular Terebra- 

 tula, pi. LV.* fig. 58, 59. 



T. orlicidaris. Sowerbv, VI. p. 68, pi. 535, fig. 3. 



L^nifoniily convex ; lesser valve orbicular, the larger with a 

 large incurved beak ; 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. Anoinia 

 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 Martixi. — Martin's Terebratula, pi. 

 LV.» fig. 79, 80. 



T. Martini. Mantell, Geo. Sus. p. 131. T. pisHin. 

 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 JIarl, Ilamsey and Folkstonc, and the Under Green- 

 sand, Isle of Wight and Blackdown. 



75. Terebratula flabellulum. — The Fan Terebratula, 

 pi. LV.* fig. 63, 64. 



T.fabellula. Sowerby, VI. p. 67, pi. 533, fig. 1. 



Depressed ; beak straight, rectangular, and projecting ; 

 lesser valve transversely obovate ; surface with about sixteen 

 simple rounded plaits. 

 Great Oolite, Ancliff, Wiltshire. 



76. Terebratula pug.nus. — The Fist-like Terebratula, 

 pi. LV. fig. 49. 



T. pugnui. Sowerby, V. p. 155, pi. 497. Phillips, Geo. 

 York. II. p. 223, pi. 12, fig. 17. lb. Pal. Foss. p. 87, pi. 35, 

 fig. 156. Conch. Anomite.') piiffnus ; Martin, Pet. Derb. pi. 

 22, fig. 4, 5. Atri/jHi pugmis ; 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, BoUand, Derbyshire, Ireland. 

 Devonian Series, Plymouth. 



This species is Uable to great variety. 



77. Terebratula acuminata. — The Acuminated Tere- 

 bratula, pi. IN.* fig. 66 to 74. 



T. acuminata. Sowerby, IV. p. 23, pi. 324, fig. 1. Phillips, 

 Geo. York. II. 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 stria;. 



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 plaits ; with or without 



lateral plaits, fig. 66, 67, 68 ; the young, fig. 7-2. 

 h. Mesial plaits variable ; with or without lateral plaits ; 

 whole surface sharply pointed. 

 VARiErv 2. — Front arched, with mesial plaits, fig. 69 ; young of the 



same, 70, 71. 73. 

 Vakietv Plkata, 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, pi. LV.* fig. 85, and pi. VI. fig. 45, 46. 



Terehratula tetrahedra. Sowerby, I. p. 191, pi. 83, fig. 4, 

 and T. media, fig. 5, Liet. Pet. pi. 41, fig. 1. 



Obtusely deltoidal, gibbose ; general form a tetraedon, 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. 



Kclloway'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 cordiformis. — The Heart-shaped Tere- 

 bratula, pi. 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 

 three 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, pi. LV.* fig. 96, 97. 



T. crumena. Sowerby, I. p. 190, fig. 2, 2*, and 3. 

 Anomileg crumena. JIartyn. Pet. Derbs. pi. 36, fig. 4. 

 2m 



