VERMES. 73 



A 1. GORDIUS GESSEEENSIS Planaria Gesserensis. Mutter. 



Probably the Planaria Gesserensis of Miiller should have a place here, 

 for it does not seem to belong to the genus selected for its reception. 



Length three inches and a half ; figure nearly linear ; extremities 

 obtuse ; six or more black specks around the anterior margin. A slit 

 below indicates the mouth. Colour universally different shades of green ; 

 sometimes tending to brown or pale carnation. Numerous lighter nar- 

 row circles, at considerable intervals, with a minute pale speck on the 

 side of each, environ the body, resembling faint annulations. 



A considerable quantity of glutinous, or almost silky matter, is 

 secreted by the body. This secretion diminishes in abundance, propor- 

 tionably to the duration of confinement. 



The animal sometimes feeds on mussel. It dwells under stones on 

 the shore. 



In confinement it reposes thus, or among mud during the day ; and 

 if several be together, they associate at night on the side of their vessel, 

 above the surface of the water. 



Specimens have survived two years. 







PLATE X. Fia. 5. 

 A. 2. GORDIUS ALBICANS Whitish Gordius. Plate XII. Figs. 5 a, 6. 



I speak with diffidence of this, which is a littoral animal, assigning 

 it also only a provisional place, for I have not succeeded in ascertaining 

 such features as are sufficiently prominent. 



Length two inches and a half ; breadth the sixteenth of an inch ; 

 form linear, somewhat flattened ; extremities obtuse. Plate XII. fig. 5 a. 

 On the anterior margin are numerous black specks, and behind them, at 

 some intervals, two clusters of specks, also black. All these are very 

 minute, and scarcely to be examined without decollation, fig. G. Colour 

 of specimens universally from dingy white to dark grey. Sometimes a 

 lighter line runs down the back, and a waved intestine may be discovered. 



K 



