NUCULANA ATTENUATA. 197 



whicli forms the boundary of the escutcheon. At the posterior end the lines are 

 bent upwards and twisted forwards over this ridge, and are less well marked, 

 giving rise to a wavy appearance. Here and there on the surface of the valve the 

 regularity of the marking is interfered with by deeper lines, especially near the 

 ventral margin. The valves are closed all round. 



Dimensions (PI. XV, fig. 3). — An average-sized specimen from Thornton, in my 

 Collection, measures — 



Antero-posteriorly . . . .28 mm. 



Dorso-ventrally (at umbo) . . .12 mm. 



From side to side . . . . 6'5 mm. 



The measurements of the type have not been given, as this specimen 

 (PI. XV, fig. 1) is imperfect posteriorly. 



Localities. — England : Shales in Belling-burn, Lewis-burn, above Plashetts 

 Coal, Falstone-burn, the Redesdale Ironstone and Shales, Northumberland 

 Carboniferous Shales, Penton, Cumberland. Scotland : Upper Limestone Series 

 Gare ; Robroyston ; Orchard ; "Williamswood ; and Waulk Mill Glen, near Glasgow 

 Dairy at Swindridge and Linn Spout, below the Linn Limestone. Lower Lime 

 stone Series : Craigenglen ; shale above Hosie Limestone, Campsie, and Thornton 

 Lingula Ironstone, 1st Kingshaw and 1st Calmy Limestones, Carluke, Newfield 

 High Blantyre; East Kilbride in the Calderwood Cement and Limestone Shales 

 also at Lickprivick, Daloch Quarry, Fife. Calciferous Sandstone series : in Cal 

 careous bands east and west of Pittenween Harbour, Fife. Ireland : Lower 

 Limestone Shale of the Townland of Ballyduff, river Bunnow, King's Co. ; East 

 of Fair Head, Ballycastle ; in Arenaceous shale at Larganmore, Bangor; Yellow 

 Sandstone, Bruckless, Dunkineely. 



Observations. — This species has the widest distribution both vertically and 

 horizontally of all the genus, of which it is the largest form. It is fairly common 

 in the neighbourhood of Glasgow, and nearly always occurs with Nucula gibbosa. 

 Figured by Ure as one form of " multiarticulate cockle," Fleming gave the shell 

 a specific name. As in the case of Nucula gibbosa, Phillips appears to have been 

 unaware that the species had been described, and identified it with N. claviformis 

 of Sowerby's ' Mineral Conchology,' which is a Jurassic species, the figured 

 specimen being stated to have come from Northamptonshire, but other specimens 

 are said to have been found " in rounded masses of grey limestone in the alluvial 

 deposits so common in many parts of Norfolk and Suffolk." Phillips's shell 

 evidently belongs to the genus Nuculana, but the specific name claviformis cannot 

 be retained for it. 



I have examined the type specimens of N. claviformis in the Sowerby Collection 

 of the British Museum (Nat. Hist.), Cromwell Road, and am bound to admit a 

 very close similarity between the Liassic and Carboniferous forms. The former, 



