202 



CONCHIFERA. 



Vexeeicardia. 



5. Pleurobhynchus longipennis. — The Long-Winged 

 Pleurorbynchus, pi. LXXXII. fig. 10. 



Transversely and much, elongated ; hinge-line nearly 

 straight ; body deltoidal, with fine radiating stri;e, crossed by 

 some irregular thin lines of growth ; centre of the valves 

 risincr into a prominent keel-shaped projection, which emanates 

 from the beaks, on which portion the striie are double, and 

 much closer than towards the sides ; rings, consisting of 

 greatly lengthened, smooth, wing-shaped processes, that on 

 the anterior side shortest, and acutely pointed ; the other, 

 broader throughout, and a little obtuse at its termination, and 

 with a few nearly obsolete transverse ribs at its point ; length 

 not quite three-eighths ; breadth up4vards of an inch. 



This beautiful shell is in the cabinet of my friend, Dr Fleming, of 

 Broughton View, Pendleton, who found it at Dovedale, Derbyshire, in 

 the Carboniferous Limestone. 



6. PLEURORnvNcnus MiNAX. — The Menacing Pleurorbyn- 

 chus. pi. LXXXII. figs. 17 and 25. 



P. rninax. Phillips, Geo. York, II. p. 210, pi. 5, fig. 27. 

 Pal. Foss. p. 33, pi. 17, fig- 60. Cardium alwformc. Sower- 

 by, VI. p. 100, pi. 552, fig. 2, (the lower shell.) 



Deltoidal, transversely elongated ; gibbous anteriorly, with 

 a contracted, slightly concave space around the umbo ; poste- 

 rior side conically elongated ; beaks anterior ; surface with 

 many equal, longitudinal, divergent ribs, except on the cordi- 

 forra anterior space, where they are much finer than on the 

 other portions, and are distinctly separated by the ring which 

 circumscribes the depression. 



The Carboniferous Limestone, Bolland and Kildare, and 

 Devonian Rocks, Bradley and Halberton. 



7. Plkurorhynchus trigonalis. — The Trigonal Pleuro- 

 rbynchus, pi. LXXXII. figs. 12 and 19. 



P. trigonalis. Phillips, Geo. York, II. p. 211, pi. 5, 

 figs. 30, 31, 32. 



Elongated, horse-hoof shaped ; gibbose anteriorly, with a 

 short smooth wing ; oblique ; hinge-line nearly straight ; pos- 

 terior side elongated, and somewhat wedge-shaped ; obliquely 

 obtuse at the termination, which, as well as the body, is 

 covered with many flat, divergent, longitudinal ribs. 



The Carboniferous Limestone, Bolland. 



2. Cardiola interrupta. — The Interrupted Cardiola, pi. 

 LXXXII. fig. 32. 



C. interriipta. Sowerby, Sil. Syst. pt. II. p. 617, pi. 8, fig. 5. 



Ovately cordiform and sub-compressed ; beaks nearly cen- 

 tral and short ; surface covered with many deep concentric 

 furrows, and more numerous longitudinal divergent ones, 

 which are less deep than the others. 



The Lower Ludlow Rock, Breidden Hills ; Garden House 

 Quarry, near Aymestry ; Radnor Forest, &c. 



Genus XX VL—MY0C0NCHA.—S'02r«»-Jj/. 



Bivalve, equivalve, oblique, sides very unequal ; hinge with 

 an elongated oblique tooth in the left valve, and provided with 

 an external ligament, which is seated in a deep groove ; beaks 

 placed close to the posterior extremity ; destitute of a sinus in 

 the impression of the mantle. 



1. Myoconciia crassa. — Thick Myoconcha, pi. LXXXIII. 

 figs. 35, 36. 



M. crassa. Sowerby, V. p. 103, pi. 467. 



Longitudinally elongated; its length nearly twice its width; 

 convex ; slightly curved, and pointed at the beaks ; surface 

 almost smooth, with a few concentric lines of growth ; sub- 

 stance of the shell thick, and the valves rather shallow. 



In the young condition there are three or four elevated striie crossed 

 by lines of growth. 



The Inferior Oolite, Dundry and Brakenridge. 



Family V.— CONCHACEA. 



Shells with throe primary teeth at least in one valve, and 

 the other generally with the same number, but in some in- 

 stances fewer. 



Sdb-ditision I.— marine. 



Generally destitute of lateral teeth. 



Genus XXV.— CARDIOLA.— B/-o(/«n>. 



Shell equivalve, oblique, inequilateral ; beaks prominent and 

 curved ; hinge-line long, with a flat area ; surface concentric- 

 ally furrowed. 



The shells of this genus are highly characteristic of the 

 lower members of the Upper Silurian Rocks, and are spread 

 over a wide extent of country. 



1. Cardiola fibrosa. — The Fibrous Cardiola, pi. LXXXII. 

 fig. 31. 



C. fibrosa. Sowerby, Sil. Syst. pt. II. p. 617, pi. 8, fig. 4. 



Cordiform ; beaks acuminated and elongated ; slightly in- 

 curved ; upper portion of the surface smooth, with a few con- 

 centric furrows ; lower portion with longitudinal strise, finely 

 decussated by numerous transverse striw. 



The Lower Ludlow Rock, Ludlow ; Welchpool, Maryknoll, 

 Dingle, &c. 



Genus XXVII.— VENERICARDIA.—Zrtwar<-/5:. 



Shell equivalve, inequilateral, sub-orbicular, the surface ge- 

 nerally with longitudinal radiating ribs or furrows ; two oblique 

 primary teeth, directed to the same side ; substance of the 

 shell thick. 



1. Venericardia planicosta. — The Flat-ribbed Veneri- 

 cardia, pi. LXXXIII. fig. 23. 



V. planicosta. Sowerby, I. p. 107, pi. 5. 



Somewhat heart-shaped ; rather smooth, with about twenty 

 flat, broad, curved, longitudinal ribs, and narrow, shallow, in- 

 tervening furrows ; on the internal posterior margin a few 

 large crenulations, which do not extend to the margin ; beaks 

 much incurved ; substance of the shell very thick and ponder- 

 ous ; hinge very large and powerful. 



The London Clay, Blackdown. 



2. Venericardia scalaris. — The Ladder Venericardia, 

 pi. LXXXIII. fig. 24. 



