LECTURE X. 
124 
punctilious exactness through all the Linnaean ge- 
nera of the Mollusca Nuda, and I shall therefore se- 
lect only the chief or principal kinds. Some of these 
genera contain animals of a long worm-like form, 
and seem, as it were, to connect in some degree the 
insect tribe with that of the Vermes; since, at first 
view they much resemble the animals of the genus 
Scolopendra or Centipede among Insects. Of these 
the genus Nereis may be taken as an example. The 
generic character consists in having a long body, 
furnished along each side with groups of feather- 
shaped tentacula, or feelers, according to Linnaeus, 
but which, in reality, are to be considered as so 
many branchiae or respiratory organs. The most 
conspicuous species is the Nereis gigantea of Lin- 
naeus, measuring from twelve to fifteen inches in 
length, about three quarters of an inch in breadth, 
and furnished along each side, from head to tail, 
with a triple row of the above-mentioned feather- 
shaped organs. Its colour is brown, with irides- 
cent variations, according to the cast of light. In 
the Gmelinian Edition of the Systema Naturag of 
Linnaeus this animal is more properly referred to 
a genus called Terehella, and is the Terebella ca- 
runculata of that edition. 
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