Terebratula. 



MOLLUSCA. 



135 



Upper Greensand, Chute Farm; Gault, Cackerton and Huiit- 

 stanton ; Lower Greensand, Parham and Saiidgate. 



42. Teuebuatuua sph^euoidai.is The Sp?proidal Tere- 

 bratula, pi. LV.» fig. 36, 37. 



T. sphferoidalis. Sowerby, V. p. 49, pi. 43.5, fig. 3. 

 Nearly spheroidal, very slightly compresseil; beak produced, 

 and incurved ; edges of valves even ; surface smooth. 

 Inferior Oolite, Dundry, Somersetshire. 



43. Terebratula subrotunda The Subrotund Tere- 

 bratula, pi. LV.* fig. 40, 41. 



T. subrotunda. Sowerby, I. p. 45, pi. 15, fig. 1, 2. 



Nearly circular, compressed; both valves regularly and equally 

 convex ; beak short, very slightly curved, and angular on each 

 side ; surface smooth. 



In some specimens the larger valve is ii little deeper than tlie other. 



Upper and Lower Chalk, Norfolk, Lewis, and Hamsey. 



44. Terebratula obovata. — The Obovate Terebratula, 

 pi. LV. fig. 43. 



T. ohovata. Sowerby, L p. 228, pi. 101, fig. 5. 



Obovate; sides slightly rounded; subdepressed; margin rather 

 flat ; base nearly parallel, bounded by two nearly obsolete plaits ; 

 beak rather produced. 



Lias, Chatley, Somersetshire. 



45. Terebratula proava The Great-Grandfather Te- 

 rebratula, pi. LV.* fig. 52. 



T. proava. Phillips, IL p. 223, pi. 12, fig. 37. 



Oblong ; larger valve with the beak considerably produced ; 

 having a scjuare mesial fold ; valves with numerous, rather ob- 

 tuse, and large radiating ribs. 



Carbuniferons Limestone, BoUand, Yorkshire. 



4(). Terebratula bidentata The Two-toothed Tere- 

 bratula, pi. LVL fig. 31, 32. 



T. bidentala. Sowerby, Sil. Syst. p. C2o, pi. 12, fig. 13 «. 

 Dahnan, 1. c. p. 142, pi. G, fig. 5. Hist. Act. Holm. 1S2G, pi. 

 7, fig. 5. 



Triangular, smooth, depressed; strongly and acutely plaited, 

 about eight of which in the front arc raised. Length three 

 lines ; width three lines and a half. 



Wenlock Limestone, Dudley and Abberley. 



47. Terebratula cuneata — The Wedge-shaped Tere- 

 bratula, pi. LV.* fig. 1, 2. 



T. cuneata. Sowerby, Sil. Syst. p. G25, pi. 12, fig. 13. Dal- 

 main. Act. Holm. pi. G, fig. 3. Hist. Pet. Suec. p. 81, pi. 23, 

 fig. 5. 



Triangular, its length exceeding its width; beak of ihe larger 

 valve straight, and produced ; surface v.ith from ten to twelve 

 plaits, of which .': few in the front are elevated. Length half 

 an inch ; depth of each valve two lines. 



Wenlock Limestone, Wenlock; Dudley, Lincoln Hill, and 

 Abberley. 



48. Terebratula bifera — The Double Terebratula, pi. 

 LVL fig. 76, 77. 



T. hifera. Phillips, Pal Fos. p. 84, pi. 34, fig. 154. 



Tetrahcdral, with foin- of the angles rounded, two of the 

 sides almost straight, the other two concave; beak acute; upper 

 valve trilobate, the middle one longest, and elevated towards 

 the base ; surface with numerous, fine, radiating stria;, which 

 are bifurcate, at unccpial distances from the beaks, particularly 

 towards the margins, where they are from 50 to GO in number. 



Devonian Shales, Hope, near Torquay. 



49. Terebratula deflexa. — The Bending Terebratula, 

 pi. LV.* fig. 81, 82. 



T. deflexa. Sowerby, Sil. Syst. p. G25, pi. 12, fig. 14. 



Transversely obovate, gibbose ; lower valve with a sinus ; 

 beaks small, and adpressed; with about twenty-four sharp plaits, 

 of vvhicli the four o ■ five central ones in front are turned down- 

 wards. Length nearly five lines; width six lines; depth four 

 lines and a half. 



A peculiarity in this species is the sinus heing in the larger valve. 



Wenlock Limestone, Wenlock Edge. 



50. Terebratula Gallina The Fowl Terebratula, pi. 



LVL fig. 78, 79. 



T. Gallina. Brongniart, Env. de Paris, pi. 9, fig. 2. Wood- 

 ward, Geo. Nor. p. 49, pi. 6, fig. 12. 



Transversely obovate; moderately convex; lower valve with a 

 wide, central furrow; beak rather acute, and small; both valves 

 with wide, pretty large, numerous, longitudinal, divergent ribs. 



Under-Chalk formation, Harford Bridge, Norfolk. 



5L Terebratula Wilsoni Wilson's Terebratula, pi. 



LV.*fig. 90, 91. 



T. Wilsoni. Sowerby, H. p. 38, pi. 1 1 8, fig. 3. lb. Sil. Syst. 

 p. 615, pi. 6, fig. 7 a. T. lacunosa, Wahl. Dahnan, 1. c. cil. p. 

 139, pi. 6, fig. 1. Hisinger, Pet. Suec. p. 80, pi. 23, fig. 3. 



Circular, plaited; valves compressed near the beaks; base 

 cylindrical, the seven central plaits elevated, margin acutely 

 dentated, and with nine or ten plaits on each side ; front sinus 

 deep. 



This species is highly characteristic of the central Ludlow 

 Rock, Aymestry Limestone, Salop; Radnor, Hereford; Aymes- 

 try, and Eastnor Park. 



52. Terebratula Unguis. — The Cloven Terebratula, 

 pi. LVL fig. 36. 



T. Unguis. Sowerby, Sil. Syst. p. 640, pi. 21, fig. 13. 

 Orbicular, much inflated; beak incurved; with about twelve 

 large, sharp plaits. Length 5i lines ; width 5 lines. 

 Caradoc Sandstone, Horderley and Welshpool. 



53. Terebratula pusilla The Slender Terebratula, 



pi. LVL fig. 18. 



T. jiusilla. Sowerby, Sil. Syst. p. 611, pi. 21, fig. 18. 

 Almoct globose, with about fourteen sharp plaits, four of them 

 elevated on the base. Diameter nearly four lines. 

 Lower Silurian Rocks, Cefn, Rhyddan, Llandovery. 



54. Terebhatula tripartita. — The Three-parted Tere- 

 bratula, pi. LVL fig. 29. 



T. tripartita. Sowerby, Sil. Syst. p. C41, pi. 21, fig. 15. 



Transversely oval, convex; with from fifteen to twenty rough 

 plates, frequently furcated; centre much elevated, so as to divide 

 the surface into three nearly equal parts. Length half an inch ; 

 width one inch and two lines. 



Caradoc Sandstone, Golcugoed, Llandovery. 



55. Terebratula decemplicata. — The Ten-plaited Te- 

 rebratula, pi. LV.* fig. 88. 



T. decemplicata. Sowerby, Sil. Syst. p. 641, pi. 21, fig. 17. 



Almost globular; beaks small, rather acute; with ten angular 

 plaits, two of them much elevated on the base. Length four 

 lines ; width four lines and a half. 



Caradoc Sandstone, Eastnor Park ; Ankerdine Hill ; May 

 Hill; Prescoed Common, Usk. 



