Now I think no one will dispute that the ovigerous frena in the one family are strictly homologous with the branchiae
of the other family; indeed, they graduate into each other.
Single pair of branchiae
on chaetiger 1 situated just posterior to pair of palps; branchiaeapinnate, flattened, with undulating lateral edges, almost equal in length to palps and appearing similar to them Finger-like extensions of lateral.
The shell-boring polychaete species were identified on the basis of fifth setiger chaetae, prostomium and pygidium morphology, and branchiae
pilocollaris are similar in the start of the branchiae
and the absence of posterior notopodial spines, but differ with respect to the maximum number of hooded hooks per fascicle and the presence of unidentate hooks posteriorly (Blake & Kudenov 1978).
Soon the crustacean encounters another creature, "the great fan worm" and Painleve reveals the worm's branchiae
and vibratory cilia through high magnification.