256 Macteay MemoriaL Vouvume. 
so far as I have observed differ widely from one another, though this statement may 
be qualified by our lack of knowledge concerning the males. They are universally 
found congregated about the roots of plants or in the axils of their leaves, where they 
thrive by gnawing at the epidermis and the subjacent cells. There can be no doubt 
that they sometimes occur in sufficient numbers to do visible injury, as witness the 
following observations : 
The edible part of three bunches of nice-looking celery bought of a Chinaman 
in Sydney was cut off as far up as it was tender,—nearly to the first leaflets. It was 
washed by hand in a tin dish in tank water, free from nematodes. The washings gave 
about 200-300 nematodes as follows. 
1. Mononchus longicaudatus, Cobb, very abundant ; 
bo 
Rhabditis sp.? less abundant ; 
3. Plectus parietinus, Bast., in numbers equalling the last ; 
4. Diplogaster trichuris, Cobb, a few ; 
5. Mononchus sp.? few ; 
6 
. Dorylaimus sp.? two at least. 
The leaves were also washed ; one nematode, a JZononchus, was found. 
These observations lead me to believe that the damage these worms are capable 
of doing to plants, especially young seedlings, is considerable, though there is as yet 
a dearth of evidence on that point. 
Kay. 
Female sexual organ single: Cheeks thin, i.e., pharynx one-half as wide as the head ; 
teeth basal— 
Armeduwithithree equalateethienstseciesitslies ccs teristtecsteceie mace euitels ectoactedsteasises 1. digiturus. 
Ar meduwithrarsingletsmallitootheesasercsscrsmeiee-tereteeseese saree inecieeaccstit 2. gymnolaimus. 
Female sexual organs double: Cheeks thick, i.e., pharynx less than one-half as wide as 
the head ; dorsal tooth if present, central. 
Length not much above half a millimetre..................sccecesseeerseseececeeneees 3. crassiusculus. 
Length at least one millimetre. 
Head contracted opposite the pharynx...................0cseescorsrseresecerece 4. Tunbridgensis. 
Head not so contracted. 
Dorsal tooth opposed by two large ventral submedian ones......... .. 95, tridentatus. 
Dorsal tooth not opposed by others of any size. 
Tail conoid and ventrally arcuate. 
PNR ELH BIS) Fen aonoptioce sos ong sbdanBaBeponODNTAGoNO NEO HI0G00 GeI00E 6. brachyurus. 
