Vol. 50.] THE COAL-FORMATION OF NOVA SCOTIA. 441 



Goldfussiana. The original drawing in 'Acadian Geology ' does not 

 show the gradually expanding posterior end, and would give the idea 

 that the original was an Anthracosia. I think the specimen from 

 the McGill College Collection labelled Naiadites elongatus belongs 

 to this species. This specimen is nearly 1 inch long, and shows the 

 typical shape and contour. 



Naiadites anqulatus (Dawson) I consider to be \ A ., • \\ 



J v ' |_ Anthracosia J 



a pretty little form of typical shape. In the original drawing the 

 posterior-superior angle is too much prolonged backward. 



Anthracomya ovalis is a somewhat larger, more tumid shell than 

 Naiadites elongatus, to which it approaches. I think that the shells 

 in a block of Millstone Grit from Puversdale belong to this form ; if 

 so, it is interesting to note the presence of the same form in the 

 Upper Coal Measures of the Joggins. 



Anthracomya la>vis is very similar to a shell which is obtained, 

 only crushed flat, from the Wigan coal-field ; the English specimens 

 are, however, larger. 



Prof. Amalizky has fallen into error as to the value of the term 

 Naiadites, and in his work on the Anthracosidae of the Russian 

 Permian, 1892, has erected Naiadites into a genus of the new 

 family Anthracosidae, reserving the term for a set of shells totally 

 different from the majority of those for which the name was 

 invented. I have shown above that originally the genus included 



Naiadites carbonarius. Anthracomya lesvis. 



„ elongatus. f Carbonicola 1 , , 



Anthracomya arenacea. \ Anthracosia j J 



„ ovalis. I 



I shall take an early opportunity of combating other views on 

 this subject contained in Prof. Amalizky's work. 



EXPLANATION OF PLATE XX. 



Coal-Measure shells from the South Joggins. The figures are of the natural 

 size, when not otherwise stated. 



Fi". 1. Naiadites, sp. Elongate form. (Unfortunately the artist has inverted 

 the figure.) 



2. Naiadites carbonarius (Dawson). 



3. „ „ showing interior. Muscle-pits. 



4. Anthracomya arenacea (Dawson). 



5. ,, ,> probably young. 



6. „ ,. probably young. 

 7 Anthracomya elongata (Dawson). X 2. 



8. „ ,, „ X2. 



9. „ „ ,. X2. 

 10. „ „ „ X2. 



1 It is highly probable that the term Anthracosia, King, must give way to 

 Carbonicola, M'Coy, on the ground of priority, although the latter's description 

 of the hinge-plate is erroneous. 



