MOLLUSCA (EXCEPT CEPHALOPODA). 
139 
(Fig. 74 a), wliicli had a very wide distribution during this Gallery- 
Age (Ouralian). Marine forms are Avimlopecten 2 ^cqJ!/racms, VIII. 
Pinna costata, and JShceulana attcimata from Scotland. 
Among lamellibranchs from the IMountain Limestone are the 
peculiarly shaped Conocardium and various species of Gardio- 
morplia. Poddononiya Bechcri is widely distributed in the 
Lower and Middle Carboniferous, often occurring in abundance 
and giving its name to certain beds in this coiintry and on 
the Continent (Fig. 74 i). Tlie gastropods of Lower Carboni- 
Fig. 74. — Carboniferous Lamellibranchs. a, Carbonicola [Anthracosia\ 
robusta, Upper Coal Measures; § natural .size, b, Posidonomya Bechcri, 
Middle Carboniferous, North Devon ; natural size. (Table-case 15.) 
ferous age contain many genera not hitherto noticed ; among 
these Macrochcilus, the loose-coiled Plianerotinus, Euonqyhalus, 
and the wide-mouthed Bellerophon are conspicuous ; a large 
shell of KaticoiJsis retains the operculum, lofty-spired forms 
are represented only by Murchisonia and Loxoncma ; Mov/i-- 
loiiia is a fore-runner of Plmrotomaria ; Platyccras [Ca 2 mlus\ 
often occurs on the ventral surface of crinoids, living on 
the food-particles that they reject. 
Devonian. During this epoch the sea existed where now 
are found fossils similar to those found in the Devonian 
limestones and slates of the Continent. The rocks that were 
at the same time being deposited over the rest of the British 
area are for the most part known as Old Bed Sandstone, and 
seem to have been formed in lakes or estuaries. Evidence 
of this is furnished by the large shells related to the modern Table-case 
fresh-water mmssel, and called Arclianodon Jultcsi. Specimens 
of this, the oldest non-marine lamellibranch as yet known, wall^ases 
come from rocks of Upper Devonian age in Northumberland, 7 & 8. 
IMonmouth, and Kiltorcan in S. Ireland. The marine forms Table^case 
i'rom the south-west of England are mostly Middle Devonian 
gastropods from the collections of the late W. A^icary and 
