178 CARBONIFEROUS LAMELLIBRANCHIATA. 



Nucula gibbosa, Fleming, 1828. Plate XIV, figs. 4 — 15. 



Multiarticulate cockle, Tire, 1793. Nat. Hist. Ruthergleii, p. 310, pi. xv, fig. 6. 

 Nucula gibbosa, Fleming, 1828. British Animals, p. 403. 



— tumida, Phillips, 1836. Geol. Yorkshire, p. 210, pi. v, fig. 15. 



— — Portlock, 1843. Geol. Report Londonderry, &c, p. 439. 



— gibbosa, M'Coy, 1845. Carbonif. Fossils Ireland, p. 69. 



— tumida, de Verneuil, 1846. Bull. Soc. geol. France, torn, iii, p. 455. 



— gibbosa, Brown, 1849. Fossil Conchology, p. 1S7, pi. lxxvi, fig. 79. 

 CrPBiCAEDiA tumida, d'Orbigny, 1850. Prodrome paleontol., p. 130. 

 Leda gibbosa, de Bychholt, 1853. Melanges paleontol., part 1, p. 148. 



? — Sancti-Adellnt, de BycTcliolt, 1853. Ibid., p. 149, pi. xvii, figs. 1 and 2. 

 Nucula gibbosa, M'Coy, 1855. Brit. Pal. Fossils, p. 512. 

 Non — — Wardle, 1863. In Sleigh's Ancient History of Leek, p. 285, 



pi. iii, fig. 7. 

 Ctenodonta gibbosa, Salter, 1866. Mem. Geol. Surv. Great Britain, Geology 



Country round Stockport,Macclesfield, Congleton, 

 and Leek, pp. 92, 93. 

 Nucula gibbosa, Bonier, 1876. Lethaea Geogn., pi. xliv, figs. 13 a — c. 

 Ctenodonta gibbosa, Bigsby, 1878. Thesaurus Devonico-Carbonif'erus, p. 302. 

 Nucula pebgibbosa, de Koninch, 1885. Annales Musee Eoy. Hist. Nat. de 



Belgique, vol. xi, p. 134, pi. xiii, figs. 21 — 

 23 ; pi. xxvi, figs. 55 — 58. 



— gibbosa, Btheridge, 1886. Brit. Foss., part 1, Palaeozoic, p. 287. 



Specific Characters. — Shell triangularly and somewhat obliquely ovate-oblong, 

 very regularly gibbose, the greatest gibbosity being about the central point of the 

 valves. The anterior end is very short, and contracted from above downwards, 

 the anterior-inferior angle being somewhat obtusely rounded and produced 

 forwards, thus forming the most anterior part of the valve. The ventral margin 

 is straight at first, and is directed downwards and backwards ; a little posterior to 

 its central point it becomes very convex, and arches upwards to pass into the 

 posterior border, which is semi-elliptically rounded. The hinge-line is arcuate. 



The umbones are very tumid, raised above the hinge-line, with the beaks 

 contiguous, depressed, incurved, and twisted forwards. They are situated in the 

 anterior third of the shell. The valves are regularly swollen, and there is no 

 defined or flattened posterior slope. There is a well-marked, deep, cordate 

 depression in front of the umbones, occupying the position of the lunule. 



Interior. — The hinge-plate is thick, and the hinge consists of two sets of teeth, 

 one anterior and one posterior, separated by a subumbonal hollow for the cartilage. 

 The teeth are smaller towards the centre, and become gradually larger as they recede. 

 They are placed on the hinge-plate vertically, and are V-shaped, the apices of the 



