Peverell family crest

[Tonks]

No: HPFGUIDX 154323

Has anyone come up with anything about the Peverell family? Why is that 
the Slytherin family?  This is what I have found so far.

Bradford Peverell is a village in west Dorset, England, situated in the 
Frome valley two miles north west of Dorchester on the A37 road. The 
village has a population of 344 (2001).

Thomas Peverell was a Bishop in England in 1407

Here is a link to the coat of arms.
http://www.houseofnames.com/coatofarms_details.asp?sId=&s=Peverell 

Does anyone know what the symbols on the coat of arms are called. I see 
there is a place that explains the meaning if you only knew what the 
symbol is called to start with.

Tonks_op