132 



MOLLUSCA. 



Terebratcla. 



3. Tebebbatula KtEisri. — Kline's Terebratula, pi. LII. 

 fig. 17, 18. 



T.globata. Sowerby, V. pi. 436, fig. 1. 



Subglobiilar ; both valves consideralilv inflated ; umbo small, 

 and incurvatcd ; lesser valve with a double sinus, for the recep- 

 tion of the elevated front of the other, and with slightly pro- 

 duced ridges, extending a little way towards the centre, which 

 is provided with obtuse angles, and hardly any furrows from the 

 sinuses ; surface covered with minute punctures. 



Fullers' Elarth at Nanncy, near Frome, and the Inferior 

 Oolite at Cotswold Hills. 



4. Tebebrati'la perovalis — The Somewhat Oval Tere- 

 bratula, pi. LII. fig. IG, IG. 



T. perovalis. Sowerby, X. p. 54, pl. 436, fig. 2, 3. 



Subovate ; both valves equally convex ; smooth ; beak in- 

 curved, and acute ; margin obtuse ; base with two elevated 

 sinuses, and an intervening depression ; these sinuses produce 

 three very obtuse ridges, two in the upper and one in front of 

 the lower valve. 



Distinguished from T. biplicata by its re^ar oval form and rather 

 acute beak. 



Inferior Oolite, Dundry and Cotswold Hill. 



5. Terebratula maxillata. — The Combe Terebratula, 

 pl. LII. fig. 29, 30. 



T. maxillata. Sowerby, V. p. 52, pl. 436, fig. 4. 



Subquadrangular, rather convex ; umbo large, and consider- 

 ably incurvated ; base with two acutely elevated sinuses, and 

 one obtuse sinus on each side ; upper valve with three well- 

 marked furrows, extending half way to the beak, and two in the 

 lower ; base rounded. 



Disting^uished from T. intermedia by the depth of the sinuses. 



Great Oolite, Stoncsfield; and Inferior Oolite, Nanney. 



6. Terebratula emabginata. — The Emarginate Tere- 

 bratula, pl. LII. fig. 22, 23. 



T. emarginata. Sowerby, V. p. 50, pl. 435, fig. 5. 



Subrhomboidal ; the larger valve convex ; the smaller one 

 nearly flat ; base emarginate, or having two angles ; the edge 

 becomes blunt when old. 



Inferior Oolite at Nunney and Cotswold Hills. 



7. Tebebbatula l«viuscula The Very Smooth Tere- 

 bratula, pl. LVI.* fig. 6. 



T. Itevitucula. Sowerby, Sil. Syst. p. 631, pl. 13, fig. 14. 

 Somewhat rhomboidal, a little convex, and smooth ; base 

 rounded; sides angular. Diameter three lines. 

 Wenlock Shale, Tynewidd and Llandovery. 



8. Tebebbatula canalis The Canalcd Terebratula, pl. 



LV.» fig. 33. 



T. canalia. Sowerby, Sil. Sysl. p. 61 1, pl. 5, fig. 18. 



Elongated, elliptical, smooth; beak slightly incurved; a nar- 

 row, longitudinal, central furrow; base emarginate- Length 

 half an inch ; width four lines and a half. 



Lower Ludlow Uocks, near Usk. 



y. Tebebbatula navicula. — The Little Ship Terebra- 

 tula, pl. LI v.* fig. 3'J, 40. 



T. navicula. Sowerby, Sil. Syst. p. 61 1 and 615, pl. 5, fig. 1 7. 



Oblong, boat -shaped, smooth; beak short, incurved; upper 

 valve almost flat, with its sides elevated and its base depressed ; 

 lower valve with an obtuse keel. Length 7 lines; width 5 lines. 



Upper Ludlow Rock, Ludlow promontory ; Clyro Hills, Had- 

 norshire, and several places in Brecon, Yeo Edge, &c. 



10. Terebratula triquetba. — The Triangular Terebra- 

 tula, pl. LII. fig. 14 and 21. 



T. triqnetra. Sowerby, V. p. 65, pl. 445, fig. 1 . 



Suliorbicular ; valves C(Hially convex; beak produced, in- 

 curved, and obtusely keel-shaped ; with a carina on each side ; 

 perforation triangular; base a little indented, producing a slight 

 concavity on the surface ; upper valve of equal length and 

 breadth, its edge level and sharp ; surface very smooth. 



Great Oolite, Felmersham, Bedfordshire. 



11. Terebbatula bullata. — The Swelled Terebratula, 

 pl. LII. fig. 25, 26. 



T. bullata. Sowerby, V. p. 49, pl. 435, fig. 4. 



Orbicular, very ventricose, depth greater than its width ; 

 beak considerably produced, and incurved; base indented, from 

 which an obscure furrow ascends a little way upwards ; edges 

 regularly level ; surface minutely punctated, which, however, is 

 only observable by the aid of a strong lens. 



Distinguished from the inflated variety of T. digona by its base being 

 narrow. 



Coral Rag, Nunney ; the Cornbrach, Atford ; the Fullers' 

 Earth, Cold Ashton. 



12. Tebebbatula obtusa The Obtuse Terebratula, pl. 



LII. fig. 27, 28. 



T. obtusa. Sowerby, V. p. 53, pl. 437, fig. 4. 



Suborbicular, somewhat depressed ; lesser valve a little wider 

 than long ; surface of both valves equally and regularly convex, 

 except near the edges, where they are abruptly bent, and form 

 a rather square, obtuse margin ; base broad, and elevated. 



Gault, Cambridgeshire. 



13. Tebebbatula bucculenta. — The Full-cheeked Tere- 

 bratula, pl. LII. fig. 37, 38. 



T. bucculenta. Sowerby, V. p. 54, pl. 438, fig. 2. 



Somewhat square ; valves nearly equal ; very convex ; beak 

 short, incurved ; sides convex ; edges nearly level, and not 

 sinuated; base considerably produced, and truncated. 



Some authors think this a variety of T. bullata, but I am of a dif- 

 ferent opinion, judging from a series of specimens. 



Coral Rag, Mallon. 



14. Tebebbatula Sella. — Tiie Saddle-formed Terebra- 

 tula, pl. LIL fig. 31, 32. 



T. Sella. Sowerby, V. p. 53, pl. 437, fig. I. 



Subquadrangular, or trigonal, convex; length and breadth 

 nearly equal ; beak obtuse, slightly curved ; sides compressed, 

 and a little rounded; base considerably elevated, and narrow; a 

 do|)ression in its centre, from whence it becomes suddenly pro- 

 duced, and occasions a hollow on each side. 



Lower Greensand, Maidstone, and Chart, near Ashford, Kent. 



15. Tebebbatula biplicata The Two-plaited Tere- 

 bratula, pl. LIV.» fig. 25. 



T. biplicata. Sowerby, I. p. 201, pl. 90. 



Oblong, gibbose ; beak large, prominent, very slightly in- 

 curved ; sides rounded ; base rather parallel, from which ema- 

 nate in the lower valve two large, distant, well defined plaits or 

 obtuse ribs, ascending two-thirds the length of the valve. 



In the young condition the phiils nru linrdly visible. 



This species is common to various beds, as the Lower Chalk, 

 Warminster; the Upper Greensand, Shute Farm, Cambridge- 

 shire, and Lyme; the Gualt, Folkstone ; Lower Greensand, 

 Kent ; and the Red Chalk, Hunstanton, Ulackdown. 



