MALARIA EXPEDITION TO NIGERIA 
3 
I. AsCARIDAE 
Shipley 6 gives the following characteristics : 'Body rather stout. A dorsal 
and two ventro-lateral lips bearing papillae. Buccal cavity distinct, seldom provided 
with chitinous armature. The oesophagus has two dilatations. The tail of the male 
is ventrally curved, and usually there are two horny spicules.' The females have a 
double ovary, and are generally oviparous. 
Genera : Ascaris, Heterakis, Oxyuris, Nematoxys, Oxysoma, and others. 
Genus Ascaris. These are polymyarian and have three lips, generally bearing 
teeth. The males have two equal spicules and a number of pre- and post-anal papillae, 
by the latter of which the best specific characters are furnished. The vulva is 
situated about the middle of the body. The ova are globular or ellipsoidal. They 
inhabit the intestines of their respective hosts. The species are very numerous. 
The life history has not been completely worked out. Infection experiments 
by feeding directly with material containing ova have always failed. It is probable 
that the larval stage is passed in some intermediary host, and Von Linstow has lately 
suggested the millipede ( lulus guttulatus ) in the case of Ascaris himbricoides. 
Genus Heterakis. Also polymyarian, distinguished from the Ascarides by the 
presence of a ventral sucker and two often unequal spicules in the male. The male 
tail has also two series of papillae symmetrically placed, and often two lateral cuticular 
expansions representing a bursa. Almost all are oviparous. They live in the 
intestines of vertebrates, particularly of birds. There are several species, found in 
the fowl, turkey, duck, pigeon, pheasant, bustard, peacock, etc. 
The life history seems to be simple, at least in the case of H. tache, the 
embryo developes from the ovum in moist media in about seventeen days, and when 
these ova containing embryos are given to pigeons, adult Heterakis are produced in 
three weeks. 
Genus Oxyuris. Meromyarian, have three slightly - projecting lips. 
Oesophagus long with distinct bulb. Males are small and scarce, have a single 
spicule ; two pairs of pre-anal papillae. Females have a long capillary tail, two 
ovaries, vulva opens in anterior portion of body. Ova are oblong and symmetrical, 
and often contain an embryo before parturition. Many species inhabit the intestines 
of man, horse, hare, rabbit, and iguana ; and others the rectum of insects, cockroach, 
water beetle, etc. 
The life history is simple — the ova, containing developed embryos are taken 
directly into the alimentary tract, and develop into adult worms. 
Genus Nematoxys. Meromyarian has very complete arrangement of muscles 
and forms a transition to the polymyarian type. 7 The whole body of both sexes is 
6. Harmer and Shipley, The Cambridge Natural History. Vol. II. P. 138. 
7. Harmer and Shipley, The Cambridge Natural History. Vol. II. P. 142. 
