Trachelina.] the INFUSORIA. 299 



observed. They are hermaphrodite. A band-hke thick 

 gland is seen in S. virens, and a bead-Uke one in other 

 species ; the former Hkewise possess a large contractile 

 bladder and green ova granules ; but in S. ambiguum the 

 latter are white. Self-division has not been observed, but 

 Ehrenberg presumes a transverse mode exists. 



490. Spirostomum virens. The green Spirostomum. 

 — Body egg-shaped, depressed, truncated anteriorly, and 

 rounded posteriorly. The back is arched, and the under 

 side flat. The green ova granules are sometimes absent. 

 {Fig. 296^.) Size l-120th; ova I-6000th. 



491. SpinosTOMVM ambiguum {Leucophrj/s, Trichoda 

 ambigua, M.) The worm-shaped Spirostomum. — Body 

 white, cylindrical, filiform, and pliant, obtuse anteriorly, 

 and truncated posteriorly ; the body extends very much 

 beyond the mouth, forming an elongated frontal region or 

 brow. The long vibrating cilii in front often appear like 

 a proboscis, and were mistaken for such by Miiller. The 

 structure of this creature, especially the mouth, is remark- 

 able, the latter being only one -fifth from the tail ; thus the 

 front or brow is very long, and the alimentary canal, first 

 inflected forwards, returns along the body ; from the 

 mouth to the anterior or top of the brow runs a long 

 ciliated furrow. Figures 297 and 298 represent this crea- 

 ture. In swimming they extend themselves, and are thus 

 readily perceived by the naked eye. Found in ditches, 

 among decaying oak leaves and rotten wood. Length 

 1-1 2th; ova 1-12000. 



Genus CXIV. Phialina. The bottle Animalcules are 

 characterized by having the frontal ciliated portion sepa- 

 rated from the body by a constriction, forming a sort of 



