
o1 
Cosp—Nematodes, mostly Australian and Fijian. 25 
? =“ a 
unusually great length of the cesophagus, which seldom occupies in adults less than 
one-fourth the length of the body. The eggs are usually ellipsoidal and somewhat 
longer than the body is wide; they are generally deposited before segmentation 
begins. The reflexed part of the ovaries is usually short, seldom reaching more than 
half-way back to the vulva. 
The tail end of the male generally resembles that of his mate in form, but differs in 
the presence of numerous low broad papillee, of which a ventral row of a dozen or more 
closely approximated ones are found in front of the anus, while several others are found 
scattered over the tail. Each of the two equal slender spicula is generally supplied 
near the middle of the shaft with an additional piece of chitin which doubtless serves 
to render it less flexible. The accessory piece is double and surrounds the spicula. 
While the genus JJononchus is one easily recognised and detined, it is one whose 
affinities have been somewhat misunderstood. It does not stand in such close 
relationship to Oxcholaimus as was formerly supposed. The structure of the pharynx 
which was thought to give it that relationship is now more clearly understood, and is 
seen to present a superficial rather than a real resemblance to the pharynx of 
Oncholatmus. The structure of the lips is very different in the two genera, those of 
Mononchus being thick, armed with a double row of prominent papillee and not 
accompanied by cephalic sete, while those of Oxcholaimus are thin, lack at any rate 
conspicuous papille and are always accompanied by sete. The inner walls of the 
pharyngeal cavity of Jononchus are moreover armed with rasp-like or file-lke 
roughnesses, not seen in Oxcholaimus. Leaving the pharynx we come to other very 
striking differences. For instance, no ventral gland has yet been demonstrated in 
Mononchus, although it probably exists, while it is never absent and is usually 
conspicuous in Oxcholaimus ; then, too, the nerve-ring in the former genus is always 
considerably in front of the middle of the cesophagus, while in the latter it is near the 
middle or behind it; again the male copulatory organs of the two genera differ widely 
from each other, and this brings to mind another difference, namely, the extreme 
rarity of males in one case and the comparative abundance in the other ; Ozcholaimus 
is marine, while J/oxonchus lives in soils and on the surface of land plants; the 
peculiar organ seen in the females of Oxcholaimus has not been met with in J/ononchus. 
These differences and others seem to me to show that only a somewhat remote 
relationship exists between these two genera. 
I am of opinion that the worms belonging to this genus can by no means be 
termed harmless to vegetation. My opinion is based on data collected during several 
years and is therefore worthy of the attention of vegetable pathologists. 
Mononchus is distributed all over the world. I have myself examined specimens 
from North America, Europe, tropical Asia, Australia and Fiji. The species do not 
’ I ’ a} 
