40 CARBONICOLA, ANTHRACOMYA, AND NAIADITES. 



thick cardinal tooth in the right valve, diverging obliquely towards the posterior 

 side, one long anterior and one long posterior lateral tooth; " and again under 

 Carbonicola subconstricta (p. 515), " Casts show the thick cardinal tooth and slender 

 elongate lamellar lateral teeth." I have never been able to see any indications of 

 " slender elongate lamellar lateral teeth," though I have examined hundreds of 

 specimens ; and further, I cannot see them in the types and specimens figured by 

 Ludwig, who also describes these teeth. Professor McKenney Hughes has kindly 

 permitted me to study all the specimens of Carbonicola and allied shells in the 

 Woodwardian Museum. There are amongst these specimens only two in which the 

 hinge-plate is visible, one of which (PI. VI, fig. 44), a portion of the right valve, 

 has an oblique posteriorly diverging cardinal tooth just under the umbo, with a 

 concavity posterior to it for the corresponding tooth of the left valve ; in the other 

 (PL VI, fig. 43) there is a different form of cardinal tooth, but in Deither can I see 

 any indication of lateral teeth. M'Coy further, in describing the hinge-characters 

 of the different species of Anthracosia, assumed that his type was invariable — an 

 assumption which could not have been based on observation, as may be seen by 

 the various forms of hinge figured in the plates of this Monograph. I cannot 

 help thinking that, having settled on the Unio-relationship of this group, the 

 typical hinge was assumed from the observation of recent forms. The specimens 

 described in M'Coy's work were all stated to be in the Woodwardian Museum, 

 but no specimen existing there now has the characteristics described under the 

 name Carbonicola. Unfortunately, Professor Amalizky, of Warsaw, has in his 

 work on the Permian Anthracosigs retained both Carbonicola, M'Coy, and 

 Anthracosia, King, as genera of a new family Anthracosidse, relying on the hinge- 

 characters given by these authors as diagnostic features. He admits, however, 

 that, owing to the absence of a drawing, it is impossible to know what M'Coy 

 really meant by " lateral teeth ; " but he considers that the forms figured and 

 described by Ludwig, and now in the Museum at Dresden, demonstrate this 

 lateral tooth. In another place, however, he remarks, " We must not forget that 

 the difference between these two genera [Anthracosia and Carbonicola] is only 

 quantitative," and proceeds to show that in a series of specimens the hinge varies 

 extremely, so that it passes from that of the form which he calls Anthracosia into 

 that which he calls Carbonicola. I am sorry to say that I consider the descriptions 

 and drawings of Ludwig altogether untrustworthy. I made a special visit to 

 Dresden with a view of testing Prof. Amalizky's statements, and was allowed by 

 the kindness of Prof. Geinitz to examine in detail the types and figured 

 specimens there. Prof. Geinitz had already raised doubts as to the value of 

 many of Ludwig's species, but had said nothing about the inventive genius dis- 

 played in the manufacture of artistic drawings. Ludwig seems to have described 

 any shell which varied in the smallest particular under a new name ; while 



