Generally the whorls of the shell increase rather regularly in size, however, species which are probably closely related, such as "A. sinistralis" (Reeve) and "A. heccarii" Tapparone-Canefri, can have quite different degrees of whorl increment. No attempt has been made to express these differences meristically, since most of the available material was inadequate for statistical treatment. Actual dimensions of the shell vary greatly both within and between species. The minimum adult size is about 21 mm high, the observed maximum about 75 mm. There is not much variation in adult size within species: only a few species, notably "A. maculiferus", "A. sinensis" and "A. entobaptus", have a variation in adult size that is greater than seven or eight millimeters in total.