190 DESCEiPTiON OF [^Folygastrica. 



its colour more than a week, but the proboscis may be well examined, 

 and preserved in that state. Length 1-240 th. Found on the surface 

 of ponds at Hampstead. 



EuGLENA spirogyra. Body extensible and cylinder- shaped, very 

 finely striated and granulated. The head is a Httle truncated, and 

 the hinder part attenuated into a short pointed tail ; colour a 

 brownish-green; motion like E. deses. Found amongst Conferva 

 and Bacillaria. Length 1 -240th to 1- 120th. 



E. pyrum. Body obliquely fluted ; when distended oval or pear- 

 shaped. The tail generally about the length of the body and 

 pointed ; colour green. Group 74 represents two of these creatures 

 magnified 400 diameters. Rarely found with any other species. I 

 have taken them at Hampstead, but not so frequently as the other 

 species. Length 1-1 152nd to l-864th. 



'E. pkuronectes {Cerearia pleuronectes, M.) Body compressed, ovato- 

 orbicular, or in the form of an obovate leaf; striated longitudinally; 

 colour green ; tail pointed one-third or one-fourth part the length of 

 the body, and colourless. Found in stagnant water. Length 1-1 152nd 

 to l-480th. 



E. longicauda. Body mostly stiff, compressed, elliptical, and leaf- 

 like ; colour green ; tail the length of the body, awl-shaped, sub- 

 ulate, and colourless. "Within this creature may often be seen a 

 yellowish-green mass of granules or ova. The very delicate vibrating 

 thread-like proboscis represented in figs. 75 and 76 has its origin 

 from the more projecting side of an indentation on the anterior edge 

 of the body, and is about two-thii-ds its length. This creature has 

 the power of twisting its body into a spiral form, as seen in fig. 75, 

 but not of contracting it. It swims freely, and mostly with a vibra- 

 tory motion, occasioned by the action of the proboscis. Found in 

 fresh water amongst Conferva and with the Bacillaria. Length 

 1 -480th to 1-1 20th. 



E. triquetra. Body leaf-shaped, three-sided, oval keeled; colour 

 green; tail shorter than the body, and colourless. See fig. 77. 

 Found amongst Lemna. Length 1 -580th. 



E. acui ( Vibrio acus, M.) Body slender, spindle-shaped, and 

 straightened in the form of a bodkin ; head attenuated, and a little 

 truncated ; taU very pointed , body green in the middle, and colour- 



