58 SUPPLEMENT , 



the action of the liquor in which these animals are preserved, 

 and is not remarked in the first state. Some species, how- 

 ever, constantly present this disposition. 



We also find, in a tolerably great number of chetopoda, 

 that the first two or three rings are provided with points, or 

 rather with spots, very distinct, constantly arranged in one 

 manner, and which have been honoured with the name of eyes, 

 though we shall presently see that there is nothing of the sort 

 in their structure, and that they do not in any wise serve the 

 purposes of vision. It is proper, however, to remark, that 

 these points are pretty nearly constant in their number, and 

 in their disposition ; so that very excellent zoological charac- 

 ters may be derived fi*om them. 



It only remains for us now to notice with respect to the ex- 

 terior of the chetopoda, their colour, and the tubes or funnels 

 which a great number of their species construct. 



A character which appears peculiar to this class of animals, 

 and which of itself alone might almost suffice to make them 

 recognized, is, that besides their proper and fixed colour, the 

 epidermis, or rather the skin, properly so called, appears 

 tinted with colours, in-adiated with magnificent reflections of 

 gold or purple. 



As to the external tube which the chetopoda often inhabit, 

 although it is often sufficiently regular and solid, it cannot, 

 however, in any manner be compared to the shell of the mol- 

 lusca, not even when there is the greatest approximation, as 

 in dentalium and siliquaria. These tubes of the chetopoda 

 are always simple excretions from their body, which are by 

 no means attached to it, and fi-om which the animal may issue 

 forth without dying immediately. We begin to observe 

 something of this kind in the mucosity with which certain 

 species line the hole, hollowed in the mud or sand which 

 they inhabit, as in the arenicolae and some lumbrici. This is 

 analogous to the mucous pellicle of the tube of the amphitritse 



