Mr.HaWoitli's ArntiigcDient n///ie \^r'c\chymous Crustacea. 105 



servations on Mr. Leslie's method of investigating the theorem 

 of tlie composition of forces, which is remarked upon with 

 some severity by Dis-Iota: but I have likely enough already 

 written more than many of your readers will bear with. You 

 shall probably- again hear from me. 



January 19, 1825. 2. 



XVII. A new binary ArTmigement of the'&YachynYous Crustacea. 

 By A. H. Haworth, Esq., FeUoiso of the Linncean and Horti- 

 cultural Societies of London, and of the Imperial Natural 

 History Society of Moscow, Src. 4'c. 



To tlie Editors of the Philosophical Magazijic a7id Journal. 



Gentlemen, 



CINCE you published the natural distribution of animated 

 nature, on a new binary or dichotomous plan, in your 

 Journal of October 1823, and which plan I now acknowledo-e to 

 be my own, I have assiduously followed up that mode of ar- 

 rangement; and I continue to find that it actually brings to- 

 gether the most closely allied productions of nature, not only 

 more easily, but more naturally and more certainly than 

 an}' other I have yet observed — I mean at least as far as I have 

 tried it ; although its various groups fall far less frequently 

 into fives than I had at first expected. 



In support of these i-emarks I send you hereunder a con- 

 tinuation of one of the branches (t!ie Crabs) of my last table ; 

 or, to speak more in the language of modern writers, the 

 Brachyurous Crustacea of the most recent authors on this in- 

 tricate branch of natural science. 



Tills present table extends no further than to the published 

 genera (on this subject) of Lamarck, Latreille, Leach, and 

 Desmarest; but it is quite capable of extension to the remotest 

 species or most trivial variety that can ever occur. 



Hoping that this little communication may find admission 

 into your next Magazine, 



I remain, gentlemen, 



Yours, &.C. 

 Queen's Elm, Chelsea, Nov. 10, IHM. \^ II_ Ha worth. 



P.S. 'Yha generic names in the table are always in italics, to 

 distinguish them promj)tly from all others. 



Vol. 65. No. 322. /(Va 1825. O CHUSTA- 



