1898] THE LATE LAMENTED LATREILLE 241 



consideration [European lobster and crayfish] in Fabricius's works was 

 undoubtedly derived from the ' Sy sterna Naturae,' wherein (in the 

 twelfth edition) Cancer gammarus stands as No. 62, Cancer astacus 

 as No. 63, in the genus Cancer. A better, though not a valid, 

 claim might be set up for A. /luviatilis as Fabricius's implied type 

 of his genus Adacus, since that species is tlie Cancer astacus of 

 Linnaeus." 



On such a sul)ject the imputation of bad faith can only make 

 one fancy that he who imputes it has been listening to the old 

 machiavellian advice, " You have no case ; abuse the plaintiff's 

 attorney." Between scientific comrades such innuendoes should 

 surely be dispensed with, and they are almost always a tactical 

 mistake, since retaliation is often only too tempting and too 

 easy. But the whole passage seems founded on misconcep- 

 tions. " It is not true," Dr Faxon says, " that the first species 

 is presumabl}'- the author's implied type." There is really no 

 question at all about what is implied or what is to be presumed, 

 but only about the rule convenient to follow, when an author has 

 himself left us in the dark. In that case to follow the rule of 

 priority is not merely not unreasonable, but truly the simplest and 

 most consistent plan that could be adopted. It is an astonishing 

 argument to urge that Fabricius could not have intended the lobster 

 to be the type of his genus Astacus, because he followed Linnaeus 

 in giving it precedence. It is, besides, a plain matter-of-fact, that 

 in arranging the species of this genus, Fabricius by no means 

 slavishly follows the Linnean order. But that point need not be 

 laboured, since Dr Faxon takes his stand on a rule not affected by 

 it, a rule laid down long after the time of Fabricius and Latreille. 

 According to this rule or recommendation, " When the evidence as 

 to the original type of a genus is not perfectly clear and indisputable, 

 then the person who first sub-divides the genus may affix the original 

 name to any portion of it at his discretion, and no later author has 

 a right to transfer that name to any other part of the original 

 genus." Whether wisely or not, that rule gives a special privilege 

 of ignoring strict priority to persons who deal with what may some- 

 times be a very difficult and troublesome task. We have now to con- 

 sider the retrospective action of that rule upon the question before us. 

 It is not disputed that until 1819 the genus Astacus contained 

 both the European lobster and the European crayfish. Then Leach 

 assigned the latter to a new genus, Potamohius, that is to say, he 

 first subdivided the genus Astacus as it then stood, and he affixed 

 the original name to the lobster. You may say he followed the 

 rule of strict priority. You may say he did what he did at his dis- 

 cretion. To persons of commonplace intellect like myself it must 

 seem as if, either way, his names were bound to stand. The illus- 



