Although it was known that certain diseases of domestic animals in wales were caused by parasitic worms, the systematic study of the economic importance of these worms did not begin until 1874, when Dr. Cobbold and a Mr. Rees Lloyd from Brecon investigated the “disastrous epizoöty” in the case of welsh mountain ponies.

This eelworm, only just visible to the naked eye, and quite common in vinegar in all parts of the world, has long been known to zoologists, and indeed was an object of keen interest and discussion to the naturalists of the seventeenth century. Petrus Borellus [3], for instance, enthusiastic over the recent adoption of the microscope for researches in natural history, published in 1656 his “Observationum Microcospicarum Centuria,” in which he leads off with a note “De Vermibus aceti.” In the twelfth edition of the “Systema Naturae” (1767), Linnaeus included a species redivivum in that final genus of the Regnum Animale so appropriately named Chaos. This species of animal he says, “Habitat in Aceto & Glutine Bibliopegorum.”.

This small species of Ankylostome worm was found in the small intestine of a golden cat (Felis temmincki) from Sumatra, in association with numerous specimens of Ancylostoma caninum, A. braziliense and Strongyloides sp. It has been experimentally transmitted to the domestic cat.

The cuticle shews not only transverse striations but numerous very fine longitudinal striations.

Like Ancylostoma, the body shews a distinct longitudinal torsion, and when the dorsal aspect of the cephalic opening is facing upwards, the posterior extremity is displaced laterally. The body is narrowed anteriorly, terminating in a pyriform buccal capsule which, as in Ancybostoma, opens dorsally. The anterior end does not form a hook– like bend as in Necator and forms allied to it.

A certain amount of confusion still exists as to the terminology to be adopted in discussing the various stages in the life cycle of the nematoda. This appears to be largely due to a difference of opinion as to the termination of each stage.

After a larva has reached a certain size, it commences to change in form and completes this process by shedding its cuticle. This change in form is the lethargus. It may or may not immediately escape from the cast cuticle, but when it does, the ecdysis is complete. The form which emerges is morphologically identical with the form inside the cuticle after the completion of the lethargus.

This accordingly gives a double choice as to the exact end of the stage. It may be during the lethargus, when the morphology of the form is changing, or it may be at the moment when the larva leaves the cast cuticle. The interval between these periods is slight in some cases but is considerable in the case of the infective stage. As the physiological end of the stage seems to coincide with the lethargus, I have accordingly based my nomenclature on it.

Hardy (1850) gave a description of some eelworms occurring in leaf-galls on the grass Festuca ovina and named them Vibrio graminis.