150 



CONCHIFERA. 



Plicatula. 



canaliculated appendage ; and with its umbo curved towards 

 the wing ; beak of tlie opposite valve rather short. 



The Upper Greensand, Western Lines, Isle of Wight, and 

 the Greensand, Blackdown and LjTne Regis. 



24. GRYPna;A mima. — The Mimic Gryphaea. 

 Gryphma mima. Phillips, Geo. York, I. pi. 4, fig. 6. 

 The Coralline Oolite, Blalton, and Calcareous Grit. 



25. Grypd.ea suilla. The Swine Gryphaea, pi. LXL* 



fig. 14. 



G. milla. Goldfuss, p. 30, pi. 85, fig. 4. 



Sub-orbicular, with concentric striated laminae ; the su- 

 perior valve plain ; the inferior one with a short blunt oblique 

 beak ; the lateral edges of the lips turned much inwards. 



The Lias, near Cheltenham. 



26. Gryph^a virgula.— The Fallen Gryphaja, pi. 

 LXVI.*» figs. 25, 26. 



Exogyra virgula. Sowerby, Geo. Tr. 2d Ser. IV. pi. 23, 

 fig. 10. Goldfuss, pi. 86, fig. 3. 



Greatly elongated and arcuated ; one valve convex, with 

 elevated lines, the other flat. 



The Kimmeridge Clay, Aylesbury, Buckinghamshire. 



27. Gryph^a inhjEREns. — The Inherent Gryphaea. 

 G. inha-rens. Phillips, Geo. York, I. p. 1 63. 



The Coral Rag and Calcareous Grit, Malton, &c. 



28. GRYPH.EA cymbium. — The Boat Gryphaea, pi. LXL* 



figs. 22, 23. 



G. cymhium. Goldfuss, p. 29, pi. 85, fig. 1. 



Oblou'T-ovate ; the superior valve concave, concentrically 

 striated ; the lower valve boat-shaped, and concentrically 

 lineated and striated ; beak acute and turned to one side ; 

 length 5 1 inches; breadth 3^. 



Inferior Oolite, Cotswold Hills. 



29. Gryphaea decussata. — The Decussated Gryphaea, 

 pi. LXL* figs. 15, 16. 



G. decussata. Goldfuss, II. p. 35, pi. 86, fig. 11. 



The lower valve oblong-oval, convex, with the apex later- 

 ally attached ; surface with decussated waved striaj. 



The Chalk, Northfleet. 



go. GRYPHiEA AUUiLA. The Eagle-beaked Gryphaea, pi. 

 iXL* figs. 17, 18, 19. 



G. aquila. Goldfuss, pi. 87, fig. 3. 



Obliquely sub-triangular, larger valve deep, with an undu- 

 lated ridge, emanating from the beak and ending on the base, 

 from whence the side is abruptly flattened, and v^rinkled ob- 

 liquely, with an undulating margin ; from the ridge to the 

 posterior side the valve gradually slopes, and its surface is 

 transversely waved and wrinkled longitudinally towards the 

 base ; beak large, and much turned to one side ; upper 

 valve flat, with an obtuse beak ; smooth and uneven in the 

 centre and the other portion with many concentric broad 



St rise. 



This is a large species, measuring 4^ inches in length and 

 3i in breadth. 



The Lower Chalk, Susses. 



Family II.— PECTINIDES. 



Ligament placed interiorly, or partly so ; shell in general 

 irregular, compact, and not foliaceous. 



Genus XIX.— PLICATULA.— Z(7jna»r/l-. 



Shell irregular, inequivalve, and destitute of ears, attenu- 

 ated at the base, rounded and plaited at the upper margin ; 

 umbones unequal and entire ; hinge with two strong, gene- 

 rally perpendicularly grooved teeth in each Talve, with 

 their points recurved, and a central cavity or pit for the 

 reception of the ligament, which is internal ; under valve 

 generally more convex than the upper one ; muscular im- 

 pressions strong, orbicular, and situate near the centre of 

 the valves. 



1. Plicattl-^ spinosa. — The Spinous Plicatula, pi. 

 LXII. figs. 1, 2. 



P. spinosa. Sowerby, III. p. 79, pi. 245. Phillips, I. p. 

 134, pi. 14, fig. 15. Goldfuss, pi. 107, fig. 1. 



Obliquely-ovate, compressed, with an angle at the beaks ; 

 deeper valve, with radiating undulations, and numerous sharp 

 spines ; opposite valve externally concave, and destitute of 

 undulations, but with irregular sharp hollow spines, which are 

 frequently hooked ; margins entire. 



Lias, Lyme Regis, and Vale of Gloucestershire, Yorkshire, 

 and Hebrides. 



2. Plicatula pectinoides. — The Pectinated Plicatula, 

 pi. LXII. 3, 4. 



P. pectinoides. Sowerby, V. p. 5, pi. 409, fig. 1. P. ra- 

 diata. Goldfuss, pi. 107, fig. 7 (?) 



Oblong-ovate, curved and depressed ; beaks curved and 

 projecting ; surface with numerous longitudinal, divergent 

 ridges, surmounted by many depressed irregular spines ; free 

 valve externally concave. When old this shell is frequently 

 sub-globose. 



Chalk Marl, Cambridge, Dover, &c. ; Lower Greensand, 

 Court-at-Street, and Broughton. 



3. Plicatula inflata. — The Inflated Plicatula, pi. LXII. 

 fig. 5. 



P. injlata. Sowerby, V. p. 6, pi. 409, fig. 2. P. spinosa. 

 Mantell, Geo. Suss. pi. 26, figs. 16, 17. Goldfuss, pi. 107, fig. 6. 



Sub-orbicular, gibbose ; both valves convex ; beaks nearly 

 central, and rather obtuse ; surface rather smooth, and pro- 

 vided with a few longitudinal ridges, mostly emanating from 

 the disc, and terminating on the base, each furnished with a 

 few depressed spines. 



Chalk Marl, Cambridge and Sussex ; Upper Greensand, 

 Petersfield and Isle of Wight. 



Genus XX.— PLAGIOSTOMA.— Z/^^yrf. 



Shell inequilateral, sub-equivalve, oblique, and provided 

 with small ears, mostly higher than long ; generally covered 

 with grooves or strife diverging from the umbones, and pass- 

 ing to the basal margin ; hinge-line transverse, straight, 

 oblique, and destitute of teeth ; umbones remote ; depression 

 for the ligament either straight or slightly angular. 



1. Plagiostoma giganteum. — The Gigantic Plagiostoma, 

 pi. LXVI. fig. 10. 



P. gigantea. Sowerby, I. p. 176, pi. 77. Goldfuss, pi. 

 101, fig. 1. 



Obliquely-oblong, sub-compressed, and deltoidal, with the 

 posterior side rounded into the front ; umbones, nearly 



