92 MOLLUSCA FROM THE CRAG. 



ligaracntal pit, somewhat contracted in the middle ; a large lanceolate-formed and well 

 defined lunule and corslet may be seen on both sides of the umbo, but the muscle 

 marks within are very slightly impressed and are indistinct, with doubtful traces of a 

 deeply sinuated form in the one by the mantle. 



I am not at all acquainted with the range of this species ; but it does not appear 

 to have a specific relationship with Nucula lezvis, Say, with which M. Nyst has con- 

 sidered his shell identical, and to which he would also unite A", limatula, a very 

 different species. It resembles in outline N. sapotilla, Gould, but seems to differ speci- 

 fically from it in the conspicuous transverse ridges, as well as in having a greater 

 number of teeth, depending upon the figure and description of that very accurate 

 observer, Dr. Gould, who would undoubtedly have pointed out the exterior ornament 

 had it possessed any. 



4. Leda caudata, Donovan. Tab. X, fig. 12, a — b. 



Arca caudata. Don. Brit. Shells, vol. iii, pi. 78, 1802. 



— minuta. Mont. Test. Brit., p. 140, 1803, not Broc. 



— — Turt. Conch. Diet., p. 11, fig. 98, 1819. 



— — W. Wood. Ind. Test., p. 47, pi. 10, fig. 44, 1828. 

 Nucula minuta. Turt. Brit. Biv., p. 178, 1822. 



— — Brown. Illust. Conch. Gr. Brit., pi. 25, fig. 18, 1827. 



— — S. Wood. Mag. Nat. Hist., New Series, vol. iv, p. 298, pi. 14, fig. 6, 



1840. 



— — Gould. Invert. Massach., p. 101, 1841. 



— rostrata. G. Sowerby. Genera No. 17, fig. 5. 



— — Mac Gill. Moll. Aberd., p. 245, 1843. 

 Leda minuta. Moller. Ind. Moll. Groenl., p. 17, 1842. 



— — King. Ann. Nat. Hist., vol. xviii, p. 240. 



— — Forbes. Mem. Geol. Surv., vol. i, p. 419, 1846. 



— caudata. Loven. Ind. Moll. Scand., p. 34, 1846. 



— — Alder. Cat. Moll. North, and Durh., p. 79, 1848. 



— — Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 226, pi. 47, figs. 12, 13, and 



pi. P, fig. 2, 1849. 



Spec. Char. Testa transversa, elongato-ovatd, vel ficiformi, convexiusculd, tenui ; con- 

 centrice striata, antice breviori, rotundatd ; postice longiori attenuatd, angulatd, et sub- 

 rostratd, margine integro. 



Shell transverse, elongato-ovate or fig-shaped, slightly convex, thin ; covered 

 with transverse or concentric striae ; anterior side the shorter, rounded, posterior 

 attenuated, angulated, and subrostrated, margin smooth. 



Longitudinal diameter, \ an inch nearly. 



Locality. Red Crag, Sutton. 



Mam. Crag, Bridlington. 



Clyde Beds. Recent, Britain, Scandinavian Seas, and North America. 



