A new species of Tetrastemma (Nemertea: Enopla: Monostiliferoidea) from Ria de Foz, north-western Spain, found living in the mantle cavity of the bivalve mollusc Scrobicularia plana. Zoological Journal of the Linnean Society, 103(3) 1991: 225-240. 227 [Zoological Record Volume 128]