CHAPTER OF CRITICISM. 141 



Saffron Walden, whereby the sum of ten guineas has been proposed to be given 

 to the writer of the best essay (to be drawn up from personal observations) upon 

 the natural history, economy, and proceedings of the 'insect injurious to Turnips 

 known under the name of the Black or Nigger Caterpillar (Athalia centifolice), 

 to be illustrated by figures of the insect in its different states, together with the 

 result of actual experiments, made for the prevention of their attacks, or the 

 destruction of the insects themselves. The essays must be accompanied by 

 testimonials of the success of the remedies proposed by the writers, and must be 

 forwarded to the Secretary of the Entomological Society, at No. 17, Old Bond- 

 Street, London, with fictitious signatures, on or before the fourth Monday in 

 January, 1833, when they will be referred to a Committee, to decide upon their 

 respective merits, after which, with the permission of the writers, the prize-essays 

 and any others of value will be published. 



The prize-essays must be accompanied by a sealed letter, indorsed with the 

 fictitious signature adopted by each writer, and including his real name and 

 address. 



I am, Sir, 



Yours very obediently, 



London, Jan. 16, 1838. J. 0. Westwood. 



QFrom the letter with which Mr. Westwood has favoured us, it will be perceived 

 that the prize-essays could not be received later than Jan. 22, but a3 the com- 

 munication furnishes the information requested by " Philander " at p. 45, we 

 have thought it best to publish it. We found it impossible to transmit Mr. 

 Westwood's epistle in MS. to " Philander " in time to be of any service. — Ed.] 



CHAPTER OF CRITICISM. 



Acephalous Mammalia, 



To the Editor of the Naturalist. 



My dear Sir, — In the fifteenth number of your Magazine (Vol. II., p. 490) 

 there is notice of a lamb without a head. These lusus natures are not so 

 extraordinary as your correspondent seems to think. In the process of the 

 development of the embryo, one part of the system may be stopped in its 

 growth whilst the rest may go on developing in a normal manner. It is on this 

 ground that all varieties of monstrous formations can be explained, and thus 

 those forms which at first sight would appear to be departures from the laws of 



u 2 



