8 
THOMPSON YATES LABORATORIES REPORT 
Life history is unknown — an insect is supposed to act as an intermediary host. 
Genus Dispharagus. These have the oesophagus divided into an anterior 
straight tubular portion, and a long thick muscular posterior portion with a bulb. 
Male tail extremity is more or less coiled, and has lateral expansions : four pre-anal 
papillae on each side, two unequal spicules. Female has a simple ovary, and is 
oviparous. The several species occur in the oesophagus and stomach of some birds. 
V. Mermithidae 
Mouth has six papillae. There is no anus. Males have two spicules and 
three rows of numerous papillae. Body of female reduced to a simple sac, crowded 
with ova. 
Genera : Mermis, Bradynema, Atractonema, AUantonema, Sphaerularia, etc. 
These are parasitic in some stage on insects, e.g., the sexually mature forms of 
genus Mermis live in damp earth, while the larval stage find their way into grass- 
hoppers, caterpillars, etc. The adult stage of Bradynema live in the body of small 
beetles, then reach the intestine, and eventually earth, where the females die, and the 
males, having developed spermatozoa in the larvae stage, now develop ova (protandrous 
hermaphroditism). The Allantonema have a somewhat similar history, as have also, 
Atractonema and Sphaerularia. The two last have the peculiar feature that at the time 
of sexual maturity a swelling — a prolapsus of the uterus and vagina — develops 
posteriorlv and grows until it far exceeds the size of the worm. Sphaerularia are 
parasitic in the body cavity of many bees (Bombyx). 
VI. Anguillulidae 
These are tor the most part free living and small. Oesophagus has two bulbs, 
the posterior without teeth. Buccal cavity contains a small spine. Males have some- 
times a bursa with no papillae ; two equal spiculae. Females have a double ovary, and 
vulva in posterior half of body ; often ovoviviparous, but the number of embryos is 
small. 
Genera : Diplogaster, Mononchus, Rhabditis, Tyknchus, Anguillula, Heterodera, etc. 
Many species of this family live in humus or decaying matter, others are 
parasitic in plants ; some live in organic matter, and some few are parasitic in animals. 
Tylenchus, Apbelenchus, and Heterodera infect plants and give rise to 'sickness' 
among clover, rye, oats, onions, beet, etc. 
Genus Rhabditis. Oesophagus has two bulbs, posterior, and sometimes with 
teeth. Buccal cavity no teeth nor spines. Males may have a caudal bursa ; often 
has six to ten papillae on bursa or in middle line, two short spicules with an accessory 
piece. Some species are hermaphrodite. 
