Miscellaneous. 123 



Dr. Leach. Ifc would be just as reasonable to write Astacus, 

 Brewster, 1814, or to assign any other genera established in the 

 article " Crustaceology " to the editor of the ' Encyclopaedia,' as it 

 would be to follow Professor Bell in ascribing " Genus 27. Potcnnobiiis^ 

 Leach's MSS.," to Samouelle, the editor of the ' Compendium ' in 

 which it first appears. It is quite a misconception to suppose that 

 Potamobius was preoccupied. In 1818 Dr. Leach had given the 

 name Potamohie in a list of crustacean genera, but the name being 

 given only in French is not of any scientific importance, and if it were, 

 it is not Potamobius ; and if it were Potamobius, it is unaccompanied 

 by any description, and therefore, as Professor Herrick had already 

 explained in 1895, it is a nomen nudum. It does not count ; it 

 can neither do good nor harm ; it does not preoccupy. 



We are told in a fine phrase that " zoologists at large " between 

 1823 and 1837 were content to accept the opinion of Desmarest 

 on the subject of Astacus. Perhaps they were, but it is difiicult to 

 see what that has to do with the matter in hand. Zoologists at 

 large are a careless lot. Desmarest both in 1825 and 1830 gives 

 Astacus 7narinus, the lobster, precedence over Astacus Jluviatilis, the 

 crayfish. He accepts Leach's genus Nephrops, and would probably 

 have accepted Leach's Potamobius, had he ever heard of it. From 

 his silence on the point it may be inferred that he never had. It 

 was he, no doubt, who by incautious language misled Professor Bell 

 into supposing that the generic name Astacus was invented by 

 Gronovius. Professor Bell in turn makes the insidious suggestion 

 that some one should invent a name to replace Potamobius. It is 

 dreadful to think that before this answer can appear someone 

 may have already done it, tempted, like Herostratus, who burned 

 down the Ephesian temple, by the grandeur of the infamy, for we 

 are told that " the inventor will throw into confusion not only 

 carcinological literature, but every text-book in every language 

 under the sun." How I tremble for those poor dear text-books, 

 induced, perhaps, to change a name or two after peacefully copying 

 one another for half a century, or to alter a sentence in the tenth 

 edition of a stereotyped volume ! It would wring tears of anguish 

 from the stoniest heart. Even some museum labels may have been 

 hastily torn up, rewritten, or reprinted, ouly to be once more can- 

 celled. But I forbear to pursue the harrowing theme. In assigning 

 the generic name Astacus to the lobster, and Potamobius to the 

 crayfish, my fortunate part has been to maintain the authority 

 of two men eminently distinguished in connexion with the British 

 Museum, Dr. "William Elford Leach and Mr. Adam White. The 

 latter upholds the names established by his great predecessor, both 

 in his ' List of the British Crustacea in the British Museum,' 

 published by order of the trustees in 1850, and in his own ' Popular 

 History ' of the same group published in 1857. I do not ask that 

 esprit cle corps should consecrate error, but when the truth happens 

 to be the heritage of one's own household, it seems a mistaken 

 policy to turn it out of doors. 



Tunbridge Wells, 

 Dec. 21, 1896. 



