124 LECTURE X. 



punctilious exactness through all the Linnsean 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 Naturae of 

 Linnceus this animal is more properly referred to 

 a genus called Terebella, and is the Terebella ca 

 runculata of that edition. 



