24. CARBONICOLA, ANTHRACOMYA, AND NATADITES. 
Unio Lottneri. Unio angulatus, Ryckholt. 
» erassidens. Cyclas elegans. 
» batilliformis. Dreissina Feldmannt. 
» Geinitzi. 3 dilatata. 
, atratus, Goldfuss. ne inflata. 
In 1861 (‘ Paleontographica,’ vol. x, pp. 21 and 22), in his memoir on the 
fresh-water shells of the (Permian ?) Coal-formation of the Ural, Ludwig figures 
and describes Anodonta (Anthracomya ?) Uralica and A. ? obstipa. 
In 1863, in another paper entitled ‘“ Die Paliontologie des Urals” (‘ Paleonto- 
graphica,’ Band x, p. 18, &c.), he mentions— 
Unio tellinarius, Goldf. Anodonta Eichwaldiana, Murchison, Keyserling, 
»  Goldfussianus, Koninck. and Verneuil. 
»  Lhuringensis, Ludwig. 5 tenera, Kichwald. 
Anodonta carbonaria, Koninck. + Uralica, Ludwig. 
- ovalis, Martin. 3 obstipa, Ludwig. 
% angulata, Rhyckholt. Cyclas obuncula, Ludwig. 
subparallela, Keyserling. Unio lepidus, Ludwig. 

Again, in 1863-4, this author published a paper in the ‘ Paleontographica,’ 
vol. xi, pp. 166, &c., on Unio pachyodon and three other species from various 
formations ; Unio Kirnensis (being a form from the Coal-measures near Kirn, which 
he says is very like U. Goldfussianus), U. compressus, and U. fabeformis from the 
Rothliegenden of Neurode. So that this author is responsible for twenty-three 
forms of Unio and four forms of Dreissina from the Coal-measures. 
The genera Unio, Anodonta, Cyrena, and Cyclas may all be here considered as 
synonymous with Carbonicola, and the author gives no reasons for this subdivision 
of the genera. 
The majority of the originals of these figures are in the Geological Museum 
at Dresden, and I was permitted by the kindness of Professor Geinitz to study 
them there. I will first quote Professor Geinitz on the subject of Ludwig’s papers, 
which criticism appeared in 1864 as an addendum to a paper by Giimbel (to be 
quoted later on in its chronological order) in the ‘ Neues Jahrbuch f. Min.,’ &., 1854, 
p- 651, where he says, ‘‘On the whole, my conclusions upon the species of Unio 
and Anodonta from the Coal-measures and Dyas, which Ludwig has so carefully 
described, differ considerably from those of that learned author ;”’ and he proceeds 
to show that many of the forms are the same. The chief thing to be noticed on 
comparing the originals with the drawings is the amount of invention and artistic 
embellishment which have made crushed and damaged specimens appear as 
perfect. In one case the fossil itself is invented, being only a concretionary mass 
(Dreissina inflata, ‘Paleontographica,’ Bd. viii, t. 1xxi, fig. 10). Many of the different 
