Oviducts are only found in jawed fish. It's not that jawless fish have some other structure, there's simply no organ for moving eggs from ovary to gonopore
The most primitive form is basically the same as a mammal's uterine tube, but just connected directly to the cloaca rather than a womb. This structure also produces the egg jelly. This form is seen today in amphibians, lungfish, and primitive ray-finned fish
Cartilaginous fish have a unique oviduct, which has a shell gland which is specialized into two parts: the upper part makes the egg jelly and the lower part makes the 'shell'. They also have a sac-like structure at the end for holding eggs before they're layed; in live-bearing sharks this is what serves as a womb
Teleosts (i.e. regular fish) also have a unique oviduct structure; there is a membrane around the ovary and the infundibulum which holds them together and prevents eggs from leaking out of the oviduct. The ovary itself is also hollow and this space sort-of acts like an extension of the oviduct. This separation of the oviduct from the rest of the abdomen appears to be unique to the teleosts
