406 DESCRIPTION OF [Rotatorfa. 



foot. AH the species possess two vibratile or wheel organs 

 upon the breast, and live of them have a frontal ciliated 

 proboscis. Longitudinal muscles are distinct in one spe- 

 cies, and two for moving the foot in six. The cesophagal 

 head has four muscles, its jaws are two-toothed in four 

 species, three-toothed in two species, but in one species 

 the cesophagal head has not been satisfactorily seen. The 

 alimentary canal is filiform, with posterior enlargement in 

 six species ; in one it appears to have pouches or pockets. 

 The glandular or cellular mass surrounding the filiform 

 part of the canal sometimes becomes distinctly coloured 

 when the creature eats coloured food, and therefore seems 

 connected with the nutritive system, and is probably a 

 convolution of coecal appendages. Biliary glands are 

 found in six species. The ovarium developes eggs, but 

 very seldom living young, hence they are only occasionally 

 viviparous ; three species possess a contractile vesicle, one 

 sexual glands. A respiratory tube at the neck is always 

 present, in some cases it is ciliated. Transverse vessels 

 are seen only in P. erythropthalma. Eyes are found 

 in all the species, and nervous ganglia connected with 

 them in P. erythropthalma; sometimes the eyes are very 

 pale, hence a single specimen may be mistaken for 

 Callidina. 



699. PHILODINA erythropthalma. The slender Philo- 

 dina is white and smooth, the eyes round, horn -like 

 processes of the foot short, and the jaws two-toothed. 

 This species is common, and found abundantly during 

 the spring and summer in water tubs, and amongst con- 

 ferva. In glass vessels it increases rapidly, and if supplied 

 occasionally with two or three stems of hay the breed may 



