91 
C. L. Boulenger 
of the alimentary canal in the classification of the family Ascaridae, the lattei 
having proposed to unite in the sub-family Anisakinae all genera in which 
the oesophagus is divided into an anterior muscular portion and a posterioi 
ventriculus of different histological structure. 
There can be no doubt that, apart from the structure of the oesophagus, 
A. vitulorum is most closely allied to A. lumbricoides and A. megalocephcda and 
must be retained in the genus Ascaris s. str. 
The species described above is evidently a common parasite in both the 
localities from which my material was obtained; when sending the specimens 
from Northern Rhodesia Mr Hornby supplied the following interesting note 
on the occurrence of the worms in that district: 
“These parasites are extraordinarily common and, when present in large 
numbers, cause scouring, wasting and death of the infested calves. Sometimes 
the small intestine bulges along its whole length owing to the number of worms 
present. Only sucking calves are affected. Growth after ingestion must be 
very rapid, as I have found hundreds of worms, from 1 to 7 inches long, in 
a calf only two weeks’ old, and adult worms predominated in a six weeks’ old 
animal. ” 
I can obtain no definite information as to the time required by A. vitulorum 
to reach maturity after the ova have been ingested, in allied species, however, 
development is known to be rather slow, the experiments of Epstein (1892) 
on human subjects and of Ransom and Foster (1920) on pigs have shown that 
for A. lumbricoides a period of about two and a half months is required for 
full development from the egg in these hosts. 
Mr Hornby’s observations suggest either that the development of A. vitu¬ 
lorum in calves is much more rapid than that of A. lumbricoides, or that prenatal 
infection must take place. The possibility of prenatal infection cannot be 
excluded in view of the recent development of our knowledge of the migrations 
of young Ascarid larvae within their hosts. 
Neveu-Lemaire (1912) has reported two cases of prenatal infestation in 
lambs with the lung-worm, Dictyocaulus filaria, other indisputable records oi 
such infections with other parasites are to be found in the literature; Cort 
(1921) has recently published an interesting summary of the known cases. 
REFERENCES. 
Baylis, H. A. (1920). On the Classification of the Ascaridae. I. The Systematic Value of 
certain Characters of the Alimentary Canal. Parasitology, xn, 253-264. 
Cort, W. W. (1921). Prenatal Infestation with parasitic Worms. Journ. Amer. Med. Ass. 
lxxvi, 170. 
Epstein, A. (1892). Ueber die Uebertragung des menschlichen Spulwurms ( Ascaris lum¬ 
bricoides). Verh. d. Versamml. d. Gesellsch. f. Kinderh. deutsch. Naturf. u. Aerzte (Wiesb.), 
v, 1-16. 
Neumann, G. (1883). Sur l’Ascaride des Botes Bovines. Rev. vet4r. (Toulouse), Aout, 1-20. 
