ations ▁Samuel ▁David ▁G ross ▁( publish er : ▁Collins , ▁printer ) ▁( 1 8 6 5 ), ▁Bi ographical ▁Sk etch ▁of ▁Charles ▁Wil kins ▁Short , ▁M . D .: ▁Form er ly ▁Professor ▁of ▁M ater ia ▁Med ica ▁and ▁Medical ▁Bot any ▁in ▁the ▁University ▁of ▁Louis ville , ▁Kentucky ▁ ▁Category : American ▁botan ists ▁Category : American ▁Pres by ter ians ▁Category : Trans ylvan ia ▁University ▁al umn i ▁Category : Trans ylvan ia ▁University ▁fac ulty ▁Category : 1 7 9 4 ▁birth s ▁Category : 1 8 6 3 ▁death s ▁Category : F ell ows ▁of ▁the ▁American ▁Academy ▁of ▁Arts ▁and ▁Sciences ▁Category : Pe ople ▁from ▁Wood ford ▁County , ▁Kentucky ▁Category : Pe ople ▁from ▁Louis ville , ▁Kentucky ▁Category : Univers ity ▁of ▁Louis ville ▁fac ulty <0x0A> </s> ▁C lav at ula ▁hel ena ▁is ▁a ▁species ▁of ▁sea ▁sn ail , ▁a ▁marine ▁g ast rop od ▁m oll usk ▁in ▁the ▁family ▁C lav at ul idae . ▁ ▁Description ▁The ▁size ▁of ▁an ▁adult ▁shell ▁var ies ▁between ▁ 3 0   mm ▁and ▁ 4 0   mm . ▁The ▁fus iform ▁shell ▁is ▁moder ately ▁long . ▁The ▁ground ▁color ▁of ▁the ▁shell ▁is ▁yellow , ▁super im posed ▁with ▁bl ot ches ▁and ▁stre aks ▁of ▁ch est nut ▁brown . ▁The ▁space ▁between ▁the ▁s ut ures ▁is ▁brown ▁in ▁the ▁anterior ▁half . ▁The ▁tele o con ch ▁is