RESUMO
Five species of lsolaimium Cobb, 1920 are described and illustrated: I. nigeriense n. sp., I. multipapillatum n. sp., I. caliIornicum, n. sp., I. papillatum Cobb, 1920, and I stictochroum Timm, 1961. A unique feature in lsolaimium, not found in any other nematode, is the presence of six cuticularized tubes surrounding the stoma and opening on the head. Order Isolaimida Cobb, 1920 is emended to accommodate this genus, which is considered to lie between the mermithoids and the dorylaimoids.
RESUMO
Different combinations of fixation and dehydration procedures for the preparation of permanent mounts of marine nematodes of the subfamily Oncholaiminae were tested and compared. Qualitatively, the best specimens resulted from Seinhorst's killing method and fixation in FAA; the dehydration procedure was of less significance. Quantitatively, no significant modification of measurements resulted from any of the methods used. Sources of error in measurements are discussed.