This may be inferred from their manner of development in the individual, as well as from a long and perfect series of gradations in different species and genera, from simple granules to ordinary spines, to perfect tridactyle pedicellariae.
Hau banakoetan duten garakeratik inferi daiteke, baita espezie eta genero ezberdinetan, bikortxo xumeetatik hasi eta arantza normaletatik igaroz pedizelario tridaktilo hobezin bilakatzeraino ageri den mailaketa-serie luze eta osobetetik ere.