224 C O N C H O L O G Y. 



The Murices conftitute my Sixteenth 

 family. As they confift of many Shells 

 that have very different fubordinate cha- 

 rafters, I (hall form different genera of 

 them ; but the fixed or eflential character 

 of the family, is an oblong and equally 

 narrow mouth length ways, (Apertura fub- 

 linearis) which runs into a fhort gutter at 

 top. Mofl authors have added another 

 charadter, that is, of always being thor- 

 ny or fpiked, bumped, or otherwife rough 

 all over the furface, like the fpikes or 

 afperities of rugged rocks, from which it 

 has obtained the Latin name of Murexj 

 the Englifh one of rocks, and the French 

 name of Rochers : however, I cannot al- 

 low this chara6ter to be a fixed or eflentia*! 

 one. 



I fhall fubdivide the family of Murices 

 or Rocks into four genera, v\z. 



GenuSr 



