X VALEDICTORY ADDRESS. 



my friends to suffer the ill effects of my own imprudence. 

 The writing of these hasty and desultory papers afforded me a 

 momentary pleasure : be the penalty also mine ; I neither 

 seek nor shun it. 



The Septenary System. — The strictures on this system are 

 more violent than the occasion warranted, and would not have 

 been admitted had any other person than myself been the 

 object of attack. I never have, and I trust never shall, reply 

 to a word of censure against myself. If just, I profit by it; 

 if unjust, I laugh at and forget it. I now as firmly as ever 

 believe in the main points of the septenary system, — the cen- 

 trality of typical forms, and the consequent approximation of 

 circles, as shown in my arrangement of the classes of Tetra- 

 pterous hexapods; — but let me add, that I consider time, 

 could scarcely be spent more idly than in endeavouring to work 

 out sevens, fives, or threes, in the families, genera, and species. 

 I regret to see minds of great natural capacity frittering away 

 their powers in this puerile employment. 



Monographia Chalciditum. — This monograph, which is per- 

 haps the most elaborate and extensive ever written, could not 

 be completed within the limits of this Magazine. Mr. Walker 

 has printed the remainder, consisting of about 250 pages, in a 

 separate volume, which I recommend to my readers as essen- 

 tial to the completion of the subject. 



Metamorphosis of Crustacea. — In the Third Volume of this 

 Magazine*^ occur some of those invaluable papers, by Dr. 

 Thompson, which have excited so much discussion among 

 Naturalists ; some having even attempted to dispute the 

 author's veracity. On this subject Mr. MacLeay has thus 

 expressed his opinion, in a work presently to be mentioned: 

 — " It is true that, in consequence of the publication of 

 Professor Rathke, some persons disputed the truth of Dr. 



'' Metamorphosis of rinnotlieres, III. 85 ; Metamorphosis of Porcellana and 

 Portunus, III. 275; Double Metamorphosis in Macropodia Phalangium ; also 

 Notes on that of Gecarcinus hydronomus, Thelphusa erythropus, Eriphsea Car- 

 ribsea, and Grapsus pelagicus, III. 370 ; Natural History and Metamorphosis of 

 Sacculina carcini, ill. 452. 



