480 On the Classification of Marine Testaceous Molhisca. 



tural composition. Aud lastly^ on arriving at the most highly 

 developed generative influences that can attach to the Inverte- 

 brata, we see an energy and activity that even exceed those qua-, 

 lities in some of the vertebrate animals, — I instance the powers 

 and locomotion of the Cephalopoda. 



The loop of our diagram may be considered as two branches, 

 or either of them a main line, and the other as a branch ; per- 

 haps the most simple view would be to regard each segment of 

 the loop a branch, springing from a common lineage, and after 

 a cometal aberration, to centre in the clara propagine of the 

 systemic and original line. 



In conclusion, we observe, that the diagram of the genera 

 shows the impossibility of an uninterrupted natural line without 

 a dislocation of congruotis affinities ; nature has not been fonned 

 on mathematical bases. We have here perhaps as much connect- 

 ive harmony as the MoUusca can receive. We do not say that 

 there may not be transpositions and certain modifications of the 

 genera to meet the particular views of malacologists, but the ge- 

 neral outline may perhaps be as near the truth as the subject 

 will admit of. If zoologists demand a natural hne, they cannot 

 have it without excluding from the grand main various families, 

 and sufiering them to fall into it, laterally and correlatively. Our 

 classification without the branches would have presented an in- 

 congruous series that no art could have arranged without un- 

 natural unions, but by them they are brought as near to each 

 other as nature will allow of. We must submit, as we cannot 

 alter her laws and dispositions. The fact of our line not accord- 

 ing a direct totality of natural affinities, proves that nature cacn- 

 not be thus arranged, because the Supreme Creator, whose hand- 

 maiden she is, has not invested her Math the power of effecting a 

 symmetry beyond what she has accomplished. 



The cause of this memoir bearing the date of May 1850, is, 

 that it was then in the hands of the editors of the ' Annals,' and 

 withdrawn for some rectifications ; it was oiiginally written in 

 1849. ,. 



I am, Gentlemen, your most obedient servant, 



William Claek. 



Exmoiith, Devon, May 22, 1851. 

 P.S. — Since I have been here I have had good opportunities of 

 examining the Conovuli, and find that the Conovulus denticulatus, 

 now seen by me for the first time, is a veiy different animal from 

 that usually called the C. bidentatus, and its synonym C. albus, 

 which I think is an undoubted Pedipes, as it has the foot deeply 

 transversely divided, which fact, formerly stated by me in the 

 ' Annals,' I have this day again verified, and I am quite certain 



