ANALYTICAL INDEX. 341 

 CHAPTER IV. continued. 



1. Introductory remarks, . . PAG E 130 



Two worms of the genus Nats inhabit the fresh-waters 



of Scotland, . . . . . ib. 



I. NAIS.- 1. NAIS LACUSTRIS, .... ib. 



Animal described, ...'.. 131 



M. Duges, propagation, ... ib. 



Dwells among the roots of the Iris and Equisetum, . ib. 



Plate XVI. explained, .... ib. 



2. NAIS PROBOSCIDEA, ..... ib. 



Animal described, .... ib. 



Motion undulatory, .... 132 



Plate XVII. explained, ... ib. 



II. LUMBRICUS, ...... ib. 



New class Annelides, .... ib. 



1. LUMBRICUS CIKRATUS The Medusa Worm. CIRRATULUS 



BOREALIS, Lamarck, . . . 133 



Animal described, . . . . . ib. 



Its appearance seems to depend on age, . 134 



Dwells in muddy fissures of rocks, . . . ib. 



Retreats from the light, ... ib. 



Ova, . ib. 



Account of specimens, .... ib. 

 Plate XVIII. explained, . . .135 



b. LUMBRICUS MARINUS ARENICOLA PISCATOEUM Lug 



Worm, . . . . . ib. 



Pyramids of sand on the sea-shore thrown up by this animal, ib. 



Called the fisherman's worm, . . . 136 



Description of the animal and its habits, . ib. 



Distinctive character of the species consists in the branchiae, 137 



2. Another species inhabits the Scottish seas, . ib. 



Form and organs of the animal described, . . ib. 



Colour very dark green, ... ib. 



Best specimens from Zetland, . . . 138 



Extensively used as bait, ... ib. 



Plate XIX. explained, . . . . ib. 



