What is "dayiceras"

Dayiceras is a finely ribbed polymorphitid eoderoceratacean ammonoid cephalopod from the Jurassic, named by Spath in 1920. The shell is evolute, coiled such that all whorls are exposed. The whorl section is compressed such as to be higher than wide. A row of fine tubercles runs along the middle of the outer rim, the venter.