W. S. MacLeay on the Natural Arrangement ofMshes. 205 



You will perhaps say, that the Cobitincc ought to represent the <S/- 

 hiridce ; but the relation between the CohitincB and Siluridce is one of 

 direct affinity, in which I perfectly agree with Swainson ; and I have 

 accordingly made the Cyprinida: and Siluridce contiguous groups in 

 the table of CLUPEINA, given on a preceding page. 



When I can secure a safe private hand, I shall beg your acceptance 

 of a copy of the third part of the ' Illustrations of the Geolog}^ of 

 South Africa.' In the mean time I must refer you to a copy which 

 I gave our friend Dr. Cantor. In page 9 of that work you will see 

 a Table which is in perfect accordance with your views of the value 

 of the word genus ; but not perhaps with your view of the word, fa- 

 mily ; nor is what I have written above consistent with the view I 

 have taken in that table of the value of the words genus and family. 

 The truth is, what in the foregoing part of this letter are called 

 Genera, are Families, and ought to end in idcB, as the peculiar desig- 

 nation of that rank of group ; but as these groups agree, wonderfullj'' 

 Avitli the extent of the old genera of Linnaeus, I left them that name 

 for your more clear comprehension of my meaning. To be consist- 

 ent, however, with myself in the above-mentioned table (page 9 of 

 the ' Illustrations'), the following ought to be the gradation of groups : 



Regnum. — Animalia. 



Subregnum. — Vertebrata. 

 Classis. — Pisces. 



Ordo. — Ostinopterygii. 

 Tribus. — Clupeina. 



Stirpes. — Cyprininse, above called ' Cyprinidae.' 



R 7 / C'yprinidcC, above called ' Pcconominse, 

 "' \ or the genus Cvjirinus.' 

 Genus. — Cyprinus. 

 Subgenus.- — ^Tinca. 



Section : — and so on to the species. 



Your table therefore, given p. 261 of your ^Monograph, is more in 

 harmon}'- (except indeed the names, which are things of artifice, and 

 have nothing to do with nature) with my table given in the ' Illustra- 

 tions' than is the foregoing letter ; and I wish you to understand, that 

 were I to publish on Fish, I would make it clearly understood, that 

 I ^^ew Linnseus's genera to be groups of the rank of families, so that 

 the groups above called Perca, Scomber, &c., ought to be called Per- 

 cidce, ScombridfP, &c. 



I have now written enough to show you how I imagine Fishes may 

 be distributed into something hke a natural arrangement. My views 

 must of course be subject to a multitude of corrections; but I think 

 they arc more connected, that is, they show more unity, than any 

 ichthyological synopsis which I have yet seen. I have worked out 

 the Plagiostoini with particular care, as my friendship with Dr. Smith 

 made me pay great attention to his unrivalled collection of Sharks 

 and Skates. If you would wish to see the conclusions at which I 

 have arrived with respect to the Plagiostomi, I shall be happy to send 

 you a sketch in some future letter. In tlie mean time, you may make 

 what use you please of what I have written in this letter, provided it 



