Connecting link refers to the living organism which shows common characteristics of two different organism groups.
Peripatus is a primitive arthropod which has annelida as well as arthropod characters.
Peripatus has annelida characters like segmented body, thin non-chitinous cuticle, segmental nephridia and parapodia-like locomotory organs.
Peripatus has the following arthropod characters: pair of jointed legs, compound eyes, tracheal respiration, and open circulatory system.
Final Answer:
So, peripatus is the connecting link between annelida and arthropoda.