Hll>I>OPODIII.M. 



CONCHIFELIA. 



195 



A. obivuriis. Sowerby, IV. p. 12, pi. 314. 



Sub-triangular, transverse ; beaks obtuse and nearly cen- 

 tral ; anterior side rather abruptly abbreviated, and moderately 

 rounded ; i>i)sterior side wedgo-sliapcd, and attenuated bolow 

 into an obtuse point ; base gradually curved ; surface smooth. 



The Magnesian Limestone, Garforth, near Leeds. 



4. AxiNus ANQULATUS. — The Angular Axinus, pi. LXXIX. 

 fig. 17. 



A. angulatus. Sowerby, IV. p. 11, pi. 31.5. 



Sub- triangular ; convex ; oblique ; breadth and length 

 nearly equal ; anterior side very short ; a little curved; pos- 

 terior side wedgc-shajicd, and depressed, with a ridge rising 

 from the beaks aud terminating on the side ; producinir an ob- 

 tuse angle on both sides ; surface nearly flat, with a few lines 

 of growth ; lunette ovate, pointed, and curved. 



The London Clay, Hampstead and Sheppy. 



5. AxiMS suLCATUs. — The Furrowed Axinus. 



Donax sulcatus. Sowerby, Geo. Tr. 2d Ser. V. pi. 39, fig.l. 



Sub- triangular ; convex; anterior side short; straight for 

 some distance below the beaks ; rounded below ; posterior side 

 wedge-shaped ; acuminated ; beaks incurved and approxi- 

 mating ; surface smooth, with a few furrows ; transverse to- 

 wards the base, which is a little rounded anteriorly, and slop- 

 ing from them upwards to the pointed extremity. 



The Coal Measures, Coalbrook Dale. 



6. Axinus rotundatcs. — The Eounded Axinus, pi. LXXIX. 

 fig.l. 



A. rotundatui. Brown, Tr. Manchester, Geo. Soc. I. j). 

 65, pi. 6, fig. 29. 



Nearly orbicular ; umbones almost central and acute, and 

 remote ; surface smootli ; length upwards of three-eighths of 

 an inch ; breadth nearly half an inch. 



The New Red Sandstone, Newtown, Slanchester. 



7. .A.XINUS PARvrs. — The Small Axinus, pi. LXXIX. f. 12. 



A. parvus. Brown, Geo. Trans. Manchester, Geo. Soc. 

 I. p. Go, pi. e. fig. 30. 



Smooth, sub-triangular ; somewhat inflated ; umbones pro- 

 minent, inflated, and contiguous ; posterior side acute, oblique, 

 and elongated ; anterior side short aud rounded ; length 

 upwards of a quarter of an inch, breadth nearly three-eighths 

 of an inch. 



The New Red Sandstone, Newtown, Manchester. 



<S. Axinus u.vuatits. — The Waved Axinus, pi. LXXIX. 

 fig. 9. 



A. undalus. Brown, Trans. Mauch. Geo. Soc. I. p. (j5, pi. 

 6, fig. 31. 



Sub-triangular, smooth, inflated ; umbones small, obtuse ; 

 sides nearly equal ; anterior side rounded ; posterior side 

 acute ; from the centre of the valve emanates a triangular 

 flexure, terminating in the basal margin ; length three-eighths, 

 breadth half an inch. 



The New Red Sandstone, Newtown, Manchester. 



9. Axinus itcillus. — Tiie Slender Axinus, pi. LXXXIX. 

 fig. 10. 



A. purillits. Brown, Trans. Manch. Geo. Soc. I. p. i)';, pi. 

 C, fig. 32. 



Triangular ; smooth ; beaks very prominent and nearly 

 central ; length one-eighth of an inch ; breadth the same. 



The New Red Sandstone, Newtown, Manchester. 



10. Axinus minimus. — The Least Axinus, pi. LXXIX. 

 figs. 2, 3. 



Nearly orbicular ; a little transverse ; beaks central, large, 

 and produced ; hiuge-line nearly straight ; surface smootli ; 

 width something more than an eighth of an inch. 



The New Red Sandstone, Newtown, Manchester. 



Family IV.— CARDIACEA. 



Primary teeth irregular both in form and situation, and, in 

 general, accompanied by one or two lateral teeth. 



Genus XIV.— PACHYMYA.—5'owe/%. 



Shell very thick, equivalve, transversely elongated ; sub- 

 lobate, with the umbones situate near the anterior extremity ; 

 ligament short, partly internal, and attached to a prominent 

 process or fulcrum ; close at both extremities. 



1. Pachy.mya gigas. — The Giant Pachymya, pi. 

 LXX VIII. figs. 11, 12. 



P.gigai. Sowerby, VI. p. 2, pi. 504, 505. Brown, Elts. 

 Foss. Couch, p. 84, pi. 7, figs. 12, 13. 



Shell gibbose, ponderous, width twice its length ; auterior 

 side small, rounded ; posterior side somewhat truncated ; a 

 ridge in both valves, emanating at the umbones, terminating 

 on the posterior margin, gives a boat-shape to the general 

 contour of the shell ; umbones very obtuse, placed rauuli to 

 one side, general surface smooth, except near the basal mar- 

 gin, where it is provided with imbricated laminai ; thickness 

 of the shell exceeding its length. 



Found in the Chalk at Dowlands, near Lyme Regis. 



Genus XV.— HIPPOPODIUM.— Conj/5«ar€. 



Shell equivalve, obliquely transverse, very thick, deep, and 

 inequilateral ; umbones incurved ; ventral margin situated so 

 as to produce a bilobate appearance ; hinge much thickened, 

 and furnished with one rugged oblique tooth. 



1. HippopoDiuM poNDEUosuM. — The Ponderous Hippo- 

 podium, pi. LXXIX figs. 20, 21. 



//. ijonderosum. Sowerby, III. p. 91, pi. 250. Fleming, 

 p. 420. Brown, Elts. Fossil Conch, p. 95, pi. 7, figs. 21 

 and 23. 



Gibbose, rugged, thick, and ponderous ; anterior lobe 

 somewhat angular, aud a little acute ; posterior lobe consider- 

 ably smaller, rounded, and following tho curvature of the 

 umbones, forms the boundary of the cordiform pit beneath 

 them, the width of which is greater than its length ; this 

 heart-shaped jiit is deep, and extends to tho binge tooth, and 

 upon which the lines of growth are well defined, and con- 

 tinue to the margin of the valve ; one valve is in depth equal 

 to its smallest diameter, which measures about half the distance 

 from the point of the anterior lobe to the beaks. 



When this sliell rests upon the prominent parts of the ante- 

 rior lobe, it bears a striking similitude to the general contour 



