186 



CONCHIFERA. 



NuCULA. 



Siib-rhomboidal, two-thirds as long as wide, rounded, ven- 

 tricose ; anteriorly mucronated, and drawn out in the form of 

 a flattened spine ; surface concentrically furrowed. 



A very minute species, found in the Great Oolite, AnclifF, 

 Wiltshire. 



22. NucuLA ANGULATA. — The Angled Nucula, pi. LXXVI. 

 figs. 31, 32. 



iV. angulata. Sowerby, V. p. 120, pi. 476, fig. 5. 



Rliomboidal, its width about once and a-half its length, front 

 rounded ; both sides equal, angular ; their lines from the sides 

 to the beaks almost straight ; most convex near the beaks ; 

 surface with fine concentric furrows, rather inconspicuous to 

 the naked eye. 



The Greensand, Blackdown. 



23. Nucula apiculata. — The Bee-like Nucula, pi. LXXVI. 

 figs. 1,3, 14.. 



N. apiculata. Sowerby, Geo. Tr. 2d. Ser. p. 342, pi. 17, 

 fig. 10. 



Sub-orbicular, convex, anterior side rounded ; posterior side 

 concave above, with the lower extremity much pointed ; sur- 

 face smooth. 



The Greensand, BlacKdown. 



24. Nucula sub-co.mpressa. — The Sub-compressed Nucula, 

 pi. LXXVI. fig .90. 



N. nndulata. Phillips, Geo. York, II. p. 210, pi. 5, f. 1«. 



Transversely ovate, compressed ; both sides equally rounded ; 

 beaks obtuse and approximating ; surface with delicate, re- 

 gular, concentric strise ; posterior side with a depressed ridge. 



The Carboniferous Limestone, BoUand. 



25. Nucula lineata. — The Lineated Nucula, pi. LXXVI. 

 figs. 8, 9, 10. 



N. lineata. Sowerby, Geo. Trans. 2d Ser. IV. p. 342, pi. 

 17, fig. 9. 



Elliptical ; beaks nearly central, small, and hardly de- 

 veloped ; anterior side rounded ; posterior side a little 

 truncated, with a short point at its superior angle ; surface 

 transversely striated, which are straighter than the lines of 

 growth, and consequently cross them twice. 



The Greensand, Blackdown. 



26. Nucula chenistriata. — The Crenistnated Nucula, pi. 

 LXXVI. fig. 91. 



N. lineata. Phillips, Pal. Fos. p. 39, pi. 18, fig. 64. 



Deltoidal, or obliquely triangular ; convex ; sides nearly 

 straight ; surface smooth, with numerous close, transverse 

 striae, every third or fourth being much more prominent than 

 the others, and crenulated on their lower edge ; beaks obtuse, 

 and approximating. 



A variety of this species has the strise all even and plain. 



The Devonian Shales, in Limestone Nodules, Boggy Point, 

 North Devonshire. 



27. Nucula sub-recurva. — The Sub-recurved >Jucula, pi. 

 LXXVI. fig. 26. 



N. sub-recur ra. Phillips, Geo. York, I. pi. 2, fig. 11. 



Transversely oblong-ovate ; anterior side somewhat turned 

 up, rather acute ; posterior side rounded ; beaks very obtuse ; 

 surface smooth. 



The Speeton Clay, Speeton, Yorkshire. 



28. Nucula axiniformis. — The Canopy-formed Nucula, 

 pl. LXXVI. fig. 34. 



N. axiniformis. Phillips, Geo. York, I. pl. 11, fig. 13. 



Transversely elongated ; anterior side terminating in an 

 acute point, the dorsal line being straight, and the basal 

 line also nearly so; posterior side sub- acute, the superior 

 line sloping downwards, and inclining suddenly from the 

 centre ; beaks obtuse ; basal line gently curved ; surface 

 smooth. 



The Blue-Wick, Inferior Oolite, Yorkshire. 



29. Nucula bivibgata. — The Double-streaked Nucula, 

 pl. LXXVI. fig. 44. 



N. bivirgata. Sowerby, Geo. Tr. 2d. Ser. IV. p. 335, pl. 

 n, fig. 8. 



Obliquely sub-triangular, wider than long ; very convex ; 

 back gently curved, ending in a sub-acute point ; posterior 

 side concave, with the extremity pointed ; base considerably 

 arcuated, beaks obtuse, and approximating; surface with two 

 sets of linear furrows, which converge towards the posterior 

 slope, where they meet at acute angles, directed towards the 

 beak of each valve ; the junction producing a regular line, 

 without forming a ridge ; lunette broad ; two transverse 

 bands near the base. 



The Gault, Folkstone. 



30. Nucula elliptica. — The Elliptical Nucula, pl. LXXVI. 

 fig. 40. 



N. elliptica. Phillips, Geo. York, I. pl. 5, tig. 6. 

 Elliptical ; both extremities rounded ; anterior side short ; 

 beaks rather large, and turned anteriorly ; surface smooth. 

 The Oxford Clay, Scarborough. 



31. Nucula pisum. — The Pea Nucula, pl. LXXVI. figs. 

 46, 47. 



Sub-orbicular ; very convex ; beaks obtuse, approximate ; 

 both sides rounded, the anterior one a little narrowed ; surface 

 smooth. 



In the Coal Measures, near Newcastle-on-Tyne, by Jlr 

 Robertson. 



32. Nucula dubia. — The Dubious Nucula, pl. LXXVI. 

 fig. 30. 



Nucula (?) Phillips, Geo. York, I. pl. 4, fig. 4. 



Transversely oblong-ovate ; both extremities pointed ; 

 beaks very obtuse and nearly central ; base gently rounded : 

 surface smooth. 



The Coralline Oolite, Malton. 



33. Nucula obtusa. — The Obtuse Nucula, pl. LXXVI. 

 fig. 49. 



N. obtusa. Sowerby, Geo. Tr. 2d. Ser. IV. pl. 17, fig. H- 

 Transversely ovate, convex, and smooth ; lunette prominent, 

 and elongated ; beaks rather obtuse. 

 The Greensand, Blackdown. 



34. Nucula complaxata. — The Flattened Nucula, pl. 

 LXXVI. fig. 27. 



N. complanata. Phillips, Geo. York, I. pl. 12, fig. 8. 



Transversely elongated, anterior side rounded ; posterior 

 side concave above, with a narrowed, sub-truncated, produ eil 

 termination ; surface smooth. 



The Upper Lias Shale, Whitby. 



35. Nucula ovat.\. — The Ovate Nucula, pl. LXXVI. 

 fig. 17. 



N. ovata. Phillips, Geo. York, I. pl. 2, fig. 10. 



Ovate ; anterior side short and obliquely truncated ; pos- 



