Cambrian until the end of Upper
identifiable on the representative of the Ptychagnostidae, the cephalon is
outlined parabolic, whereupon the maximum width is located anterior of the genal
angle. With the exception of some representatives of the Eodiscina, the
Agnostides were eyeless. The sutures (if present) are ending anterior to the
genal angle at cephalons border (proparian), The glabella is, except for the
representatives of the family Condylopygoidea, conical outlined. The
indicates a particle feeder.
of Suborder Agnostina solely featuring 2 thoracic segments (e. g.
Ptychagnostus cuyanus) whereas some representatives are fractionally featured
with 3 thorcic segments.
The tails shield is
isopygous (Gr.- rump) i. e. it's regarding to size, shape and construction
nearly identical to trilobites cephalon.