Why Peripatus is called a connecting link between

Why Peripatus is called a connecting link between annelids and arthropods?

Annelid characters of Peripatus. Have jointed parapodia like legs, nephridia for excretion and simple gut.
Arthropod characters of Peripatus claws on the legs, haemocoel, trachae for respiration and head with a pair of eyes and antennae.