by H. Harford Williams and Arlene Jones. 47 pages, illustrated. Commonwealth Institute of Helminthology, Commonwealth Agricultural Bureaux, Central Sales Branch, Farnham Royal, Slough SL2 3BN, England. 1976. £3.00
by O. Wilford Olsen, A.B., M.A., Ph.D., Head, Department of Zoology and Parasitology, Colorado State University, Fort Collins, Colorado. vii + 346 pages, illustrated. Minneapolis, Burgess Publishing Company. 1962. $6.95