Hydrocephalus (trilobite)

Hydrocephalus; Temporal range: Middle Cambrian PreꞒ Ꞓ O S D C P T J K Pg N
	Hydrocephalus carens at the National Museum (Prague)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	†Trilobita
Order:	†Redlichiida
Family:	†Paradoxididae
Genus:	†Hydrocephalus; Barrande, 1846
Species
	H. carens Barrande, 1846 (type) ; H. lyelli (Barrande, 1852) = Rejkocephalus lyelli ; H. mandiki Kordule, 1990 ; H. minor (Boeck, 1827) = Trilobites minor ; H. paradoxum (Hawle et Corda, 1847) = Paradoxides paradoxum ; H. rotundatus (Barrande, 1846) = Paradoxides rotundatus, Rejkocephalus rotundatus ; H. spinulosus Rushton, Weidner & Ebbestad, 2016 ; H. vikensis Rushton & Weidner, 2007 ;
Synonyms
	Phlysacium Hawle et Corda, 1847 ; Rejkocephalus Kordule, 1990

Hydrocephalus ("water head") is an extinct genus of redlichiid trilobite that was very common during the Middle Cambrian of Eurasia and North America, which lasted from 508 to 497 million years ago. This trilobite is up to 20 cm long and more widely built than others of the time. In comparison to other members of its family, its glabella appears swollen.