Evans, H.M. (1924)
The Poison Gland of Trygon. -Supplementary Note.
Proceedings of the Royal Society of London, Series B, 96, 491–493 DOI: 10.1098/rspb.1924.0039
Evans, H.M. (1904)
A new cestraciont spine from the lower Triassic of Idaho.
Bulletin of the Department of Geology, 3, 397–402