A MONOGRAPH 
OF THE 
DEVONIAN FAUNA 
OF THE 
SOUTH OF ENGLAND. 
VOL. II. 
Class.— LAMBLLIBRANCHIATA, Blainville, 1814. 
PelecypodAj Goldfuss, 1820. 
In describing tlie Bivalves from these rocks we are met by the difficulty that 
the interior and the hinge are hardly ever exposed, and that consequently their 
systematic position has generally to be inferred from analogy to other species 
from more favoured localities. Added to this, in so rough a matrix the margins of 
single valves have been peculiarly liable to injury in fossilization, or to destruction 
in the attempt to develop them. This necessarily gives rise to a large amount of 
doubt in the determination of some of the forms described. 
As regards the number of species, this class is fairly represented both at 
Lummaton and Wolborough, but as a rule individual specimens are extremely 
rare. Four or five species, however (e. g. Conocardium clatJirakim, Cypricardinia 
scalaris, Butotia ellijotica, and one or two Pterinese), may be regarded as common 
shells, although in no instance do they at all approach the Brachiopods in 
abundance. 
From Chudleigh we have only two species ; but one of these, Mecynodon colum- 
VOL. II. 1 
