576 



HISTORY OF SYSTEMS. 



the Planarice and Fasciolce: related, indeed, to them by 

 ancdogxj, but without any connection whatever in regard 

 to affinity. The extraordinary genus Herpa, one of the 

 splendid discoveries of Guilding, carries this analogical re- 

 semblance to the highest pitch ; so that but for the discri- 

 minating acumen of that profound observer, we should have 

 been tempted, without seeing the animal, to consider it was 

 an actual type of Planaria, in the disguise only of a Umax. 

 On these and numerous other similar facts resulting from the 

 analysis of this class, we hesitate not to place a portion of 

 Cuvier's intestinal worms as the most aberrant order of the 

 testaceous Mollusca." 



So much for the connection of the orders 5 and now ycu 

 are to remark that each of these orders must have an analo- 

 gical relation with its corresponding order of the vertebrate 

 and annulose animals, above, below, and around them. Thus 

 the Gasteropods represent, analogically, the Quadrupeds ; 

 the Dithyra, the Birds ; the Nudibranchia, the Reptiles ; the 

 Parenchymal, the Amphibians ; and the Cephalopoda, the 

 Fishes : and there is really much ingenious fancy brought 

 into play in conjuring up the correspondent resemblances— 

 the fancy, too often, it is true, unchecked by the stubborn 

 facts wherewith anatomy attempts to bar its flight. Thus 

 we are taught that the Cephalopods, here made the analogues 

 of the lowly vertebrated fishes, are higher structured than 

 the Gasteropods, which are, nevertheless, reckoned by Mr. 

 Swainson to be the counterparts, in their station, of the 

 typical Quadrupeds. 



The analogies of the Mollusca with the annulose creatures 

 is exhibited by Mr. Swainson in the following table : — 



Tribes of Testa- 

 cea. 



Gasteropoda. 



Analogical Characters. 

 Typical, the most highly organised ;• 



■li 



Classes of the 

 Ammlosa. 



head distinct, with Jong antennae or [.Ptilota. 

 tentacula. 



/Head indistinct, confounded with the - ) 

 Dithyha. \ thorax, or altogether wanting ; no IAptera. 



{ antennae or tentacula. J 



Nudibranchia. { Disc f the be % flattened, and often,. 



1 performing the office of a foot. / Annelides. 



I" The most simple in their organisation,' 



naked, and crawl upon their belly ; . Vermes. 

 L no perceptible branchia. 



fMouth surrounded by long tentacular 



or arms; soft parts of the body LCirrhipeda. 

 L generally protected by a shell. 



Pakenchymata. 



Cephalopoda. 



