Cobb — Nematodes, mostly Australian and Fijian. 7 



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; 



2. Rhabditis sp. ? less abundant ; ' 



3. Plectus parietinus, Bast., in numbers equalling the last ; 



4. Diplogaster trickuris, Cobb, a few ; 



5. Mononchus sp. ? few ; 



6. Dorylaimtis sp. ? two at least. 



The leaves were also washed ; one nematode, a Mononchus, 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. 



Key. 



Female sexual organ single : Cheeks thin, i.e., pharynx one-half as wide as the head , 

 teeth hasal — 



Armed with three equal teeth 1, digiturus. 



Armed with a single small tooth 2. gymnolaimus. 



Female sexual organs double : Cheeks thick, i.e., pluxrynx less than one-lmlf as wide as 

 the head ; dorsal tooth if present, central. 



Length not much above half a millimetre 3. crasdusculus. 



Length at least one millimetre. 



Head contracted opposite the pharynx 4. Tunhridgensis. 



Head not so contracted. 



Dorsal tooth opposed by two large ventral submedian ones 5. tridentalus. 



Dorsal tooth not opposed by others of any size. 

 Tail conoid and ventrally arcuate. 



Anusat98% 6. hrachyurus. 



