SOME AQUATIC WORMS, ETC. 173 



2. CH^ETONOTUS STTLCATUS. 



The characteristic of this form is in the deep trans- 

 verse furrows conspicuously developed on the back and 

 sides. The body is transparent, and unusually soft and 

 flexible. The posterior region between the arch of the 

 back and the caudal furcation is narrowed, and much 

 longer than in other species. The oesophagus is short, 

 being not more than one-sixth the length of the body. 



COtfCJNNUS. 



The back and sides, which are more nearly parallel 

 than in most species, are closely covered by small hemi- 

 spherical elevations arranged in oblique lines and giving 

 the animal a peculiarly neat and attractive appearance. 

 The two caudal glands are unusually large and conspic- 

 uous. 



4. Cfl^TOIsOTtTS LORICATUS. 



The scales on the back and sides are arranged in im- 

 bricated rows, the convex free margins being directed for- 

 ward. Although so completely covered, the body is very 

 flexible, the scales freely sliding over each other when 

 the animal curves to one side. The mouth is obliquely 

 placed, as may be seen when the Chaetonotus is viewed 

 in profile, and its internal margin is strongly beaded. 

 The eggs are armed by hollow papillae, or by short hol- 

 low spines whose summits are bifid or emarginate. 



5. CHAETONOTUS KHOMBOIDES. 

 This is easily recognizable by the peculiar head, the 



