70 CARBONIFEROUS LAMELLIBRANCHIATA. 



MoDiOLA FABALis, de Koniiick, 1885. Anuales Musee E. Hist. Nat. Belgique, 



vol. xi, Faune du Calcaire Carboni- 

 fere de la Belgique, 5me partie, 

 Lamellibranches, p. 179, [)1. xxviii, 

 figs. 10, 11. 

 — — Biffshi/, 1878. Tliesaurus Devonico-Carboniferus, p. 309. 



Specific Characters. — Shell oblique, transverse, gibbose, so as to be almost cylin- 

 drical, anteriorly expanded and rounded posteriorly. The anterior portion of the shell 

 is almost obsolete, and below the level of the umbones is swollen Avith bluntly rounded 

 border. The inferior border descends at first backwards and downwards with a 

 gentle curve ; it then becomes sinuous, and posteriorly is more convex where it 

 passes Avith a regular curve into the posterior border, which is expanded and rounded. 

 The hinge-line is straight, and passes insensibly into the jDosterior border in a gentle 

 curve. There is no indication of an angle. The umbones are tumid, blunt, non- 

 contiguous, and directed forwards, situated very much forwards but not terminal. 

 There is a very small and almost obsolete lunule in front of them. Proceeding 

 doAvnwards and backwards from the umbones the valves are much inflated 

 obliquely, immediately anterior to which is an oblique constriction, becoming 

 broader and deej)er as it approaches the margin of the shell. Above the con- 

 striction the valves are compressed so as to become hollowed, the posterior superior 

 angle of the shell being expanded. 



Interior. — No details of the muscle-scars are to be seen on the specimens which 

 have yet been obtained. 



Exterior. — Certain portions of the left valve of fig. 5, PI. VII, show the shell 

 to have been ornamented with fine concentric lines of growth, crowded in front. 



Dimensions. — Fig. 5, PL VII, measures — 



Antero-posteriorly . . . .20 mm. 



Dorso-ventrally .... 11mm. 



From side to side . . . .10 mm. 



Locality. — The highest bed of the Calciferous Sandstone series of St. Monans, 

 Fife. 



Observations. — The specimens figured were obtained by me v/hen I was 

 examining the coast sections of the Calciferous Sandstone beds of Fifeshire. They 

 are quite unlike any other member of the genus Modiola described from British 

 Carboniferous beds, and are distinguished by the regularly rounded posterior end 

 and tumid form. From the description and figures I have referred them to M. 

 ligonula, a species described by de Ryckholt from " I'argile carbonifcre " of Tournay. 

 His description is " mediocrement renflee, meme un peu deprimee k I'extremit^ 

 anale ; . . . . cote buccal retr(5ci et tronque ; cote anal allant en s'elargissant et 

 arrondi en avant ; cote palleal un peu baillant ; crochets presque terminaux." I 



