142 



CONCHIFERA. 



Terebratula. 



134. Terebratula crenulata. — The Crenulated Tere- 

 bratula, pi. LVI. fig. 74, 75. 



T. crenulata. Phillips, Pal. Foss. p. 85, pi. 34, fig. 152. 



Pentagonal ; beaks very obtuse and rounded, compressed ; 

 sides and base nearly parallel ; whole surface, except near the 

 umbonal regions, covered with fine numerous deep furrows, 

 with rather flat intermediate ribs. 



Devonian Shales, South Devon and Barton. 



185. Terebratula ventilabrum. — The Bellied Terebra- 

 tula, pi. LVI. fig. 84, 85. 



T. ventilahrum. Phillips, II. p. 223, pi. 12, fig. 36, 38, 39. 



Rhomboideo-deltoidal ; margins sharp, with obtuse ribs ; 

 upper valve sulcate near the beak, which is obtuse ; sides 

 nearly obliquely parallel, with five or six mesial ribs. 



Carboniferous Limestone, Bolland. 



136. Terebratula anisodonta. — The Unequal-notched 

 Terebratula, pi. LVI. fig. 58, 59. 



T. anisodonta. Phillips, Pal. Foss. p. 86, pi. 34, fig. 154. 



Transversely oval, depressed ; beak somewhat prominent ; 

 front straight, with a large angular elevation raised to a straight 

 mesial edge, which is deeply indented by six narrow rounded 

 ribs ; sides rather reflected towards the deeper valve ; broadly 

 and deeply notched by short considerably elevated ridges. 



Devonian Shales, Barton, South Devonshire. 



137. Terebratula soclalis. — The Social Terebratula. 

 T. socialis. Phillips, I. p. 112, pi. 6, fig. 8. 

 Transversely oblong-ovate ; beak short ; mesial elevation 



with four prominent ribs ; sides slightly rounded j whole sur- 

 face with very strong and rather acute ribs. 



Calcareous Grit, and KeUoway's Rock, Scarborough and 

 Hackness. 



138. Terebratula spixosa — The Spinous Terebratula, 

 pi. LVI.. fig. 1. 



T. spinosa. Smith, p. 108 ; Knorr, Tet. Dil. 2 pi. B. 4, 

 fig. 4. Phillips, Geo. York. I. p. 123, pi. 9, fig. 18. T.uspira. 

 Kdnig, Icon, fig. 219. 



Subtriangular ; beaks rather obtuse ; sides gradually round- 

 ed ; surface with rather broad longitudinal ribs, provided with 

 obtuse, somewhat distant spines. 



Great Oolite Cave, and Bath, and the Inferior Oolite. 

 Dundry ; Cheltenham, Bayeux, and Bole. 



139. Terebratula ambligonia. — The Obtuse-angled 

 Terebratula, pi. LVI.* fig. 33. 



T. amhUffona. Phillips, Pal. Foss. p. 88, pi. 35, fig. 160. 



Pentrahedral, oblong, a little convex, with the surface 

 slightly elevated ; umbones somewhat produced, from whence 

 a mesial furrow proceeds, and terminates on the basal margin, 

 on each side of which are five rather large and rounded diver- 

 gent ribs ; mesial furrow on the deep valve bounded by two 

 ribs, which are shorter than the others. 



Devonian Shales, South Devon, Barton, and Babbacombe. 



140. Terebratula sulcirostris. — ^The Furrowed-beaked 

 Terebratula, pi. LVI.* fig. 9 and 12. 



T. mlcirostris. Phillips, Geo. York. II. p. 222, pi. 12, fig. 

 31, 32. 



Rhomboideo-deltoidal ; beaks slightly developed ; central 

 area with from five to nine pretty deep divergent furrows, 

 with intermediate ribs, and producing a square projection on 

 the base ; ribs on the sides flat, and slightly defined ; edge 

 sharp ; upper valve with the furrows reaching the beak. 



This species is subject to two varieties, one of which has numerous 

 ribs, and the other with fewer. 



Carboniferous Limestone, Bolland. 



141. Terebratula laticosta. — The Broad-ribbed Tere- 

 bratula, pi. LVI.* fig. 10, 11, 63, 64. 



T. laticosta. Phillips, Pal. Foss. p. 85, pi. 34, fig. 153. 



Transversely elliptical ; beaks small, slightly produced, and 

 angulated, with a very small perforation ; front provided with 

 a mesial sinus ; about twenty obtuse, almost equal, prominent 

 ribs cover the surface ; these are more enlarged towards the 

 borders, which are obtuse, and crossed by distinct lines of 

 growth. 



There are two varieties of this species. Fig. 63 and 64 are the ordi- 

 nary form, and 10 and 1 1 the variety ; the former is from the Limestone 

 at Boggy Point, North Devon, and the latter from Barton, North 

 Devon. 



142. Terebratula lacunosa, pi. LVI.* fig. 15. 



T. lacunosa. Sowerby, Sil. Syst. p. 624, pi. 12, fig. 10. 



Transversely elliptical, with a projecting sinus ; surface 

 with numerous divergent rounded ribs, which project beyond 

 the edges; larger valve with the beak considerably incurved, 

 and both of them obtuse. 



Wenlock Limestone, Wenlock Edge ; Nash Lime Scar, and 

 Wallsall. 



Genus XIIL ORBICULA.— CwnVr. 



Shell inequivalve, nearly orbicular, compressed, generally 

 irregular in form, adherent, fiat, and attached by means of a 

 fibrous substance passing through an orifice near the centre of 

 the lower valve. Upper valve patellifomi, its vertex pos- 

 terior or nearly central ; each valve provided with four mus- 

 cular impressions, two of which are large, approximate, and 

 situate near the centre ; two smaller and more distinct ones 

 placed near the posterior margin ; those of the lower valve 

 not so well defined as the others ; near the inner extremity of 

 the orifice there is an obtuse testaceous process, destitute of 

 hinge — teeth, or ligament. 



1. Orbicula punctata. — The Punctured Orbicula, pi. 

 LVI.* fig. 54. 



0. punctata. Sowerby, Sil. Syst., p. 636, pi. 20, fig. 5. 



Lenticular, much compressed ; apex submarginal ; surface 

 with fine granulations, each of which is punctured. Diameter 

 half an inch. 



Lower Silurian Rocks, Chatwall, Caradoc. 



2. Orbicula rugata. — The Rough Orbicula, pi. LVI.' 

 fig. 57, 58. 



0. rugata. Sowerby, Sil. Syst., p. 608, pi. 4, fig. 47, 48, and 

 p. 610, pi. 5, fig. 11. 



Almost orbicular ; upper valve a much depressed cone, with 

 the surface concentrically wrinkled; lower valve nearly flat. 

 Diameter six lines, height two lines. 



Upper Ludlow Rock, Ludlow, Promontory, Richard's Castle, 

 and many other localities. 



3. Orbicula striata. — The Striated Orbicula, pi. LVI.* 

 fig. 61, 62. 



0. striata. Sowerby, Sil. Syst., p. 610, pi. 5, fig. 12. 



Orbicular, very convex ; apex defiected, marginal, covered 

 with minute radiating striae. Diameter seven lines, height 

 three lines. 



Upper Ludlow Rock, Delbury and Ludlow Hills. 



