i897. CORRESPONDENCE. 71 



The reviewer finds it difficult to appreciate the differences between Anthracomya 

 and Naiadites, and grumbles that I do not contrast them. I really did not think it 

 necessary to contrast genera of two different Families. He quotes a remark I make 

 about the difficulty of distinguishing compressed forms of one species when the 

 periostracum only is left and would maka out that I apply it to the whole genus. 

 Finally the reviewer remarks that the shells " are not described with uniformity and 

 that it is therefore difficult to compare a couple of descriptions." Surely this is 

 pure imagination on his part, for on rereading them I can only find one example of 

 a fault of this description i.e. in the case of C. Polmontensis. 



After inveighing in several places upon the absence of indications of varietal 

 forms, and the passage of species towards each other, he finds fault with the exces- 

 sive number of figures, which are numerous simply to demonstrate the facts which 

 the reviewer supposes absent. He grumbles that I have in any way allowed 

 horizonal distribution to come into the determination of Species but the answer is 

 that in the same bed the intermediate forms if any are always present but in beds 

 separated by many feet of strata this sort of evidence is necessarily absent. 



On p. 36, I find that I specially thank Mr. H. Bolton for " looking over my 

 specimens, MS. and proof ; and for several observations which have been of great 

 service to me in the preparation of the section on Carbonicola." Surely the grave 

 faults which he now finds in my work should, in common courtesy, have been 

 pointed out before publication, in the present case he forgets that every criticism he 

 makes is an attack either on his own accuracy of observation or on his character as 

 a proof-reader and adviser. Is there no etiquette in a matter of this sort, or is it 

 permissible to pretend to afford every help possible in the production of a work, but 

 at the same time to make reservations on which an attempt may be made to pull the 

 whole work to pieces at some future date ? 

 Stoke-on-Trent, Dec. 3, 96. Wheelton Hind. 



Your last issue contains a review by " H.B." of Dr. Hind's recently published 

 Monograph of Carbonicola. Anthracomya and Naiadites." Your critic is evidently 

 very inconsistent inasmuch as he points out, in the same sentence " signs of great 

 haste" and yet considers the monograph as a " valuable contribution." If there is 

 one thing more noticeable than another, in reading over the " Monog " it is that the 

 author has been most careful and deliberate in dealing with what everyone who 

 knows anything of the subject, considers a most difficult group to work. Evidence 

 of this is given in the careful and elaborate study and delineation of the interiors. 



Let us examine some of the so called omissions and commissions alleged by the 

 reviewer, and first , the replacement of name ' ' Anthracosia ' ' by that of ' ' Carbonicola. ' ' 

 Dr. Hind's reasons page 39, vol. xlviii., are quite sufficient and conclusive to authorize 

 him to drop " Anthracosia" and retain " Carbonicola." " McCoy" did describe the 

 genus, even if he gave a rather erroneous diagnosis. " King " neither described nor 

 figured. When, a year later, " King " described his Anthracosia, he gave the hinge 

 and teeth of C. aquilina, a specimen which is not characteristic of a genus but only 

 of a species. 



The demands by H. B. for absolute fixity of a species and variety are absurd, 

 inasmuch as the Carbonicola are so variable, and therefore we agree with Dr. Hind 

 that it is better to take as types those specimens which are most typical, in a certain 

 set from the same bed. It is further charged by " H. B." that no gradation of species 

 is sufficiently recognized, but if so, why has Dr. Hind given such numerous figures 

 — thirty-six for example of C. aquilina. Again, why does " H. B." think there are 

 too many figures when he so clearly recognises the necessity of comparing a large 

 series of specimens. 



Another charge is that Dr. Hind fails to distinguish what constitutes a species. 

 Will " H. B." kindly define what he thinks, exactly constitutes a species. ? With 

 regard to A. dolobrata and A. Adamsii, I have seen both specimens myself and 

 consider Dr. Hind quite correct in his naming of them. Again — species are said to 

 have been founded upon one or two specimens. This is true but, the said species 

 have received due consideration, and such naming is sometimes quite unavoidable, 



