4 SYNOPSIS OF 



It might be expected that some attempt of the application 

 of M'Leay's circular system should be made in regard to this 

 family. Swainson says that " the progression of every natural 

 series is in a circle."* In my attempts to prove this, I have 

 not been successful. That the same idea exists in the con- 

 struction of species is evident through a great number, but that 

 this idea is returned to the point at which it commenced I am 

 not prepared to assent to. 



To form a systematic, and so far as possible a natural ar- 

 rangement of this family has long occupied my serious atten- 

 tion. 



I was, from my first knowledge of the family, struck with 

 the very different aspect of the winged species, and taking the 

 hint of Lamarckjt I thought that an important division could 

 be made by separating the connate from the free shells, and 

 proposed the name of Symphynota for such as were connate. 

 I was not satisfied at that time in separating a genus of this 

 family by a character differing from that of the teeth, but pre- 

 sumed that the family would be taken up by some one, if not 

 by myself, and that the first division of it would be symphy- 

 note and .non-symphynote Natades. The numerous new 

 species which have been made known since, have satisfied me 

 that this character cannot be so extensively and usefully ap- 

 plied as I then thought it could, and that it is not in fact free 

 from the same objection which pervades so many generic 

 characters as adopted by the most intelligent naturalists, viz., 



* Swainson, in Lard. Cycl. Nat. Hist. p. 247. 

 t Vol. VI. p. 76. 



