28 



C. M. CHILD. 



tarius also it is capable of living for months in clear water in the 

 laboratory, though, as will appear below, certain interesting modi- 

 fications of shape and proportions appear under these conditions. 

 The description of structure and habits given for C. solitarius 



a— 



- a 



(Child, '03^/, p. 239 et seq.) will apply in general to this species, 

 but it may be noted here that C. (estuarii is more sensitive to ex- 

 ternal stimuli than C. solitarius. Slight contact-stimuli with 

 needles or brush produce extreme and rapid contraction when 

 the animal is normally distended with water, though it is ap- 

 parently much less sensitive when partially or wholly collapsed. 



