Trachelina.] TH E INFUSORIA. 291 



FAMILY XVII. TRACHELINA. 



This extensive family includes those polygastric animal- 

 cules which have an alimentary canal with two distinct ori- 

 fices, the receiving one lateral, the discharging one termi- 

 nal. They have no lorica. The bodies of all the genera, 

 except Phialina, are covered with vibrating cilii; these are 

 generally disposed in longitudinal rows, and those near 

 the mouth are longest. The cilii serve as organs of locomo- 

 tion. Trachelius has no neck, but the frontal portion of 

 the body is prolonged in the form of a long proboscis-like 

 lip; in Loxodes and Chilodon it is like a hatchet-shaped 

 broad lip. In Glaucoma there is a tremulous flap to the 

 mouth; and in Chilodon and Nassula the teeth sometimes 

 project before the mouth. The genera Bursaria and 

 Nassula have a thick frontal protuberance, caused by the 

 alimentary canal being curved anteriorly; numerous sto- 

 mach-cells are observable, and their reception and dis- 

 charge of coloured matter can be seen in all the genera. 

 The teeth in Chilodon and Nassula, and the violet-coloured 

 bile (gall) of the latter genus, are worthy of notice. In 

 Spirostomum the mouth is of a spiral shape; reproductive 

 organs are of a double kind in all the genera. Complete 

 transverse and longitudinal self-division is frequent, but 

 neither the formation of gemmae nor clusters are 

 observed. 



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