* Spiroxys contortus (Rudolphi, 1819) Schneider, 1866

Preamble: Because an account of L3 from fishes does not appear to be available, Bartlett & Anderson’s (1985) description of specimens from snails Lymnaea stagnalis is given here.

L3 variable in length: short ones 1.8 (1.6–2.0); longer ones—on which the remainder of the description is based—2.7 (2.5–2.9) long. Maximum width 0.064 (0.058–0.070). Anterior end with two pseudolabia, eight cephalic papillae, and two lateral amphids. Cuticle thick, with fine transverse striations. Nerve ring 0.155 (0.140– 0.160) and excretory pore 0.200 (0.190–0.220) from anterior end. Deirids 0.080 (0.065–0.095) behind excretory pore. Buccal cavity 0.019 (0.016–0.020) long. Oesophagus 0.90 (0.78–1.09) long, and divided near nerve ring into anterior muscular and posterior glandular portions (Fig. 38 A). Genital primordium oval, 1.8 (1.6–2.1) from anterior end. One post-deirid present near genital promordium. Anus 0.078 (0.070–0.090) from posterior extremity. Phasmids large, protuberant. Tail tapers to point (Fig. 38 B).

Site: mesenteries

Hosts: Ameiurus nebulosus; Perca flavescens

Distribution: Ontario

Record: Molnar et al. 1974