74 MARINE ANIMALS. 



Again, Oysters, Mussels, and Cockles immediately associate with them the 

 idea of London suppers and street stalls, while the Gasteropoda, or Snails^ 

 leave their shiny traces on the walls of damp cellars, and the Cephalopoda j 

 or Cuttle-fishes, number amongst their species some of the most formidable 

 and unsightly monsters which inhabit the unknown depths of the ocean. 

 The name Girrhopoda is derived from the occurrence of certain flexible 

 armsj the Latin word cirrus signifying a tuft of curled hair, which these 

 animals are suppose^l to resemble; the termination poda being common to 

 all those who have the power of attaching themselves or obtaining a footing 

 on any other substance, as distinguished from those which float on the bosom 

 of the waters. To the whole of this class of beings the name has been 

 given of Heterogangliata, or as possessing a different nervous system to other 

 classes. On opening the shells by which most of the MoUusks are protected, 

 they are found lined with two delicate membranes, which have been termed the 

 mantle, and which is nicely fitted to the interior of the shell. The B ranch iopoda 

 are furnished with arms, as the name implies, and these, in some of the 

 species, are enormously developed, and lie concealed within the recesses of 

 the shell, by the most at once simple and beautiful mechanism; and in some 

 of these, which are bivalve, or composed of two shells, are observed separate 

 and rudimentary ganglia. Another division of the HeterogangUata is known as 

 the Tunicata, or those which appear enveloped in their mantle, without any 

 external shell. These animals occur on most sea-coasts, and, being incapable 

 of motion, and in fact perfectly helpless, are attached either singly or in 

 bunches to Sea-coral or any other substance. Within, the animal is furnished 

 with a contractile power which, when handled, presses with great force on 

 the internal parts, and ejects water in a small stream; these go by the 

 name of Ascidians. 



We next come to the Conchifera or Oyster tribe, which are bivalves, or 

 enclosed in two shells; and little do we think, when we swallow them so 

 glibly, what a beautiful mechanism we devour, and how recently that mechanism 

 has performed in perfection its living functions. Turning from these well-known 

 animals, we encounter another family no less so, namely, the Snails, {Helix,) 

 which exhibits a much higher organization, and whose re-productive powers 

 more nearly approach those of perfect animals, which depend upon each other. 

 Here we also find the respiratory organs in a much higher state of development, 

 and muscular fibre is likewise present. The Pteropoda come next, and, as 

 somewhat a link, I imagine, between inferior fishes and the Molluscous animals, 

 are furnished with fins, by which they readily transport themselves from one 

 locality to another. The Clio horealis is an example of this race, and more 

 singularly-formed creatures can hardly be imagined; this may be illustrated 

 by the fact, that no less than three hundred and sixty thousand minute 

 suckers were counted upon the head of one of them by the aid of the 

 microscope. 



The last species which we have now to refer to is the Cuttle-fish, of which 



