38 SHELLS AXD SHELL-FISH. PART I. 



or intestinal worms, as truly belonging to this class. 

 Our reasons for this will be again adverted to. At 

 present, it will be sufficient to state, that these animals 

 are totally distinct from the true Vermes, where the 

 body is composed of articulations more or less developed, 

 and which consequently form the corresponding group 

 in the annulose circle. Nearly all of these imperfect 

 and obscurely known animals, however, partake of 

 the general character of the Testacea, in crawling or 

 adhering by their belly, beneath which, — as in the 

 Fasciolce, — there are cup-shaped disks, or suckers. 

 Analogous, in every respect, to these, are the arms of 

 the next tribe. 



(34.) In this manner, then, are we conducted to 

 the fifth and last tribe of the testaceous Mollusca, 

 — namely, the Cephalopoda, or cuttlefish. But 

 this is done by the intervention of a group of ani- 

 mals, almost as simple in their organisation as the 

 intestinal tribe last mentioned. Some of the Ptero- 

 poda, in fact, like the Parenchymata, are without head, 

 branchia, eyes, or any external members ; even the fin, 

 so universal among the Firolce, is wanting in such 

 genera as Timorenia and Monojjliora : but these, or 

 any of the Hetei'opoda, are not the animals to which 

 we must look for the typical characters of the group 

 before us. The types of the Cephalopoda, in fact, are 

 the most highly organised, and, therefore, the most 

 perfect, of all the Testacea. The appearance of these 

 animals is strange and grotesque in the extreme. 

 Their body is soft and pulpy, having the limbs ar- 

 ranged in a circle round the mouth ; these limbs per- 

 form all the offices of feet, arms, and tentacula, and, 

 in many genera, they are used also as fins. The head, 

 which, in all the other Testacea, is either wanting or 

 but slightly developed, is here large and conspicuous ; 

 while the eyes are so clear and distinct, that they re- 

 semble those of a vertebrated animal ; the mouth, from 

 the arrangement of the limbs, or, as we shall term 

 them, the arms, is consequently in the centre, like that 



