 The opening of the stylophore leads directly into the atrium in certain species in the families Vitrinidae , Parmacellidae , Helminthoglyptidae , Bradybaenidae , Urocyclidae , Ariophantidae , and Dyakiidae . The opening of the stylophore can instead lead to the penis , as is the case in some species of Aneitinae ( a subfamily of Athoracophoridae ) , Sagdidae , Euconulidae , Gastrodontidae and Onchidiidae . Alternatively , it can lead to the vagina , as in the case in some species of Ariopeltinae ( a subfamily of Oopeltidae ) , Ariolimacinae ( a subfamily of Ariolimacidae ) , Philomycidae , other species within the Bradybaenidae , and also in the Hygromiidae , Helicidae and Dyakiidae . 
