PLANARIA VELOX. 129 



anguillae suspended in the fluid, fell like a 

 flocculent substance, to whiten the dusky 

 deposit below. 



While viewing the incalculable millions 

 here concentrated together, I observed 

 some diminutive animals quickly ascending 

 the sides of a vessel, which on gaining the 

 boundaries of the element, committed them- 

 selves to its surface in swimming supine. 

 Being separated from the rest, they proved, 

 on more intimate investigation, to belong 

 to that tribe with which we have been so 

 long engaged, and possessed of properties 

 denoting their alliance with the species last 

 described. 



The planaria velox exactly resembles a 

 weaver's shuttle, and were it not from cer- 

 tain peculiarities specified by Muller, it 

 might be considered the same which he has 

 designated rostrata. Whether these pecu- 

 liarities are temporary or permanent, has 

 not been explained ; sometimes the simple 

 difference of the season of inspection may 

 persuade us, though erroneously, to insti- 



K 



