DESCEIPTION OF THE PLATES. 



FRONTISPIECE. 



Fig. 1. Group of Plumafellce. The figure to the right is of natural 

 size ; that to the left is magnified, and shows one animal 

 contracted and two expanded, with their ciliated tentacles 

 in activity. The group is fixed on a stem of sea-weed. 

 (Copied from Milne Edwards. ) 



... 2. A Cydlppe slightly magnified ; the streamers contracted. 



... 3. A Nodiluca MUiaris greatly magnified. The circular spaces 

 are vacuolse, filled with granules of food ; these are only 

 tem^Dorary, and are sometimes not visible at all. (Copied 

 from Quatrefages.) 



... 4. Group of CVaweZ/i/io?, about three times the natural size, rising 

 from a creeping stem. The two orifices open and shut rhyth- 

 mically to suck in and eject water. The lace- work structure 

 is richly ciliated, and is supposed to represent the gills of 

 the animal. (Copied from Mr Gosse.) 



PLATE II. 



Fig. 1. An Eolis coronata. 

 ... 2. A Doris Johnstoni. The two horn-like processes on the head 



are the antennae which retract, when the animal is touched, 



or removed from the water ; the coronet at the other end is 



the circle of branchial plumes. 

 ... 3. A Pholas dactylus, or rather the shell of one. (Figs. 1-3 copied 



from Woodward's Mollusca.) 

 ... 4. An Aplysia. The gills are seen under the fold of the skin, to 



the right. (Copied from Milne Edwards.) 

 ... 5. A Teredo Norvegica removed from its shell. (Copied from 



Woodward's Mollusca.) 



