CARBONICOLA. 41 
unfortunately in his earlier publications totally ignoring the work already done in 
the subject by English, Belgian, and other geologists. The figured specimens 
are, with very few exceptions, crushed, poor, incomplete, or undeveloped from the 
matrix—conditions which have not appeared either in the drawings or the text. 
Not only does he see fit to divide the genus into Unio, Anodon, and Cyrena (Cyclas) 
without advancing any differential diagnosis, and these genera into many species, 
but he invents anatomical features in the hinge, and in one case (Anodonta cicatricosa) 
indicates, in a cast left by the outer surface of the shell, the anterior and posterior 
adductor-muscle scars, not having recognised that the specimen showed the 
impression of the external surface only. In another specimen a concretion has 
been mistaken and figured for a specimen of his Dreissena inflata. 
I examined many specimens, both in Berlin and Dresden, of forms similar to 
those described by Ludwig, and in no one was I able to satisfy myself of the pre- 
sence of lateral lamellar teeth; and, moreover, I felt sure that the species were 
similar to those which had been described by previous writers. Still it is possible 
that Professor Amalizky may be wrong in considering that Ludwig meant to 
describe lateral teeth as being present. In the latter’s description of the hinge of 
his Unio securiformis (C. aquilina), of which the drawings are fairly correct, is 
found ‘‘ Das stark entwickelte Schloss besteht aus einem am Vorderende sitzenden 
gefalteten Zahn und einer runden, langsgefaltteen Leiste oben und nach hinten.” 
The question here arises as to the exact interpretation to be put on the word 
** Leiste,”’ as to whether it is to be taken as indicating a lateral tooth, or being 
used to describe the hinge-plate, such a tooth not being present in the specimen, 
but the posterior part of the hinge being a flattened vertical plate, somewhat 
irregularly rounded, surmounted by a groove for the insertion of the hgament ; 
further, in the description of the hinge of Unio Lotineri (Anthracosia acuta) the 
following expression occurs :—‘‘ Das Schloss besteht aus eimem dicken, vorsprin- 
genden, gekerbten Zahne hinter dem Wirbel [anterior], und einer langen, flachen 
Leiste vor demselben”’ [posterior]. 
I am inclined to think that what has been mistaken for the posterior lamellar 
lateral tooth is the upper edge of the flat hinge-plate, which is bounded above by 
the longitudinal groove for the insertion of the external ligament; this upper edge 
of the hinge-plate, bemg below the level of the superior border of the shell, there- 
fore becomes apparently very prominent. On this point Ludwig states, “ Das 
Ligament (Schlossband) lag ausserhalb lings der Leiste,” which, I think, bears out 
my view. The hinges of Ludwig’s Unio batilliformis, U. crassidens, and U. lepidus 
are pure artistic inventions, and are in the original specimens either very incomplete 
or partially covered up by the opposite valve. Yet these figures and the descrip- 
tions are quoted by Professor Amalizky as intermediate forms. 
Considering the great variation of hinge-structure which obtains in a single 
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