Child and adolescent psychiatrists are trained to help parents sort out whether their child's level of shyness is normal introversion or indicative of a disorder.
As of 2004, research tended to distinguish shyness from introversion.
The probability appears to be against an actual introversion of the appendage and its lamellae, as was at one time suggested by Lankester.
The introvert is not a simple one with complete range both in eversion and introversion, but is arrested in introversion by the fibrous bands at c, and similarly in eversion by the fibrous bands at b.
Each cansists of an eversible hollow tentacle provided with hooklets and capable of introversion within a mem The excretory organs consist of flame-cells, richly convoluted canaliculi, and a pair of longitudinal canals leading to the exterior by one or more pores.