NEW DATA ON A LATE DEVONIAN (FRASNIAN) CYCLOCYSTOID FROM THE ITHICA FORMATION OF NEW YORK STATE
Polytryphocycloides n. sp. is characterized by a ring of heavy marginal ossicles with two (rarely one) cupules and crests that display a unique ornamentation with subparallel rugae along the median of the crest that fan/splay laterally towards lateral striae. One specimen preserved with a complete marginal ring bears 49 marginal ossicles. The ventral surface of these plates is strongly concave as well as both the proximal and distal margins, giving it a slightly waisted appearance. In lateral view the crests are convex giving them a semi-elliptical cross section. Plates bearing two cupules are nearly twice as wide as those bearing one cupule and single cupule plates are inserted into the margin at random. The cupules are slightly longer than broad with low lateral walls that are absent proximally and distally and each bears a rounded tubercle that is slightly longer than broad. The smooth frontal plates are as tall as they are broad and are more curved ventrally than distally. Roofing plates are distally pointed and form five to six alternating rows. Imbricate radial plates are stellate in shape with two lateral processes and a shallow radial channel. The lateral processes from adjacent rays abut along their lateral margins.