Ptychagnostus

Ptychagnostus Temporal range: Middle Cambrian PreЄ Є O S D C P T J K Pg N
Ptychagnostus germanus
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	†Trilobita
Order:	†Agnostida
Family:	†Ptychagnostidae
Genus:	†Ptychagnostus Jaekel, 1909
Synonyms
Triplagnostus Linnarsson, 1869 Huarpagnostus Rusconi, 1950 Solenagnostus Whitehouse, 1936 Pentagnostus Lermontova, 1940 Aristarius Opik, 1979 Aotagnostus Opik, 1979 Acidusus Opik, 1979 Canotagnostus Rusconi, 1951 Zeteagnostus Opik, 1979

Ptychagnostus is an extinct genus of blind trilobite that lived during the Cambrian period, part of the order Agnostida. Ptychagnostidae generally do not exceed ten millimetres in length. Their remains are sometimes found in the otherwise empty tubes of the polychaete worm Selkirkia. It probably lived in the water column. Its major characteristics are lack of eyes, two lobes on the glabella, and three lobes on the pygidium.