Two new rhabdocoel turbellarians, Umagilla pacifica, sp. n. and U. karlingi sp. n. (Umagillidae), endosymbiotic with holothurians (Echinodermata) from the Great Barrier Reef; and a discussion of sclerotic structures in the female system of the Umagillidae. Zoologica Scripta, 16(4) 1987: 297-303. 299 [Zoological Record Volume 124]