4 Cobb — Nematodes, mostly Australian and Fijian. 



(Tnnbridgensis) is contracted, but in all the others is slightly expanded at the lip- 

 region. Two rows of tactile organs, each consisting of six conical innervated papiUse, 

 surround the mouth,— the outer spreading row being situated on the margin of the 

 head, while the inner row closely surrounds the mouth. These papilliB are usually of 

 uniform size, but sometimes those of one row, usually the inner, are larger than those 

 of the other. It is tolerably certain that the number of lips is three, and that each 

 lip is two-parted, though this is not an easy thing to demonstrate, owing to the fact 

 that the hps are very low and nearly confluent. The mouth-opening is small, the 

 length of _the passage leading from it to the pharynx being determined by the 

 thickness of the hps, which are uncommonly bulky and powerful. Behind the lips 

 the pharynx assumes at once its full width, which is tolerably uniform throughout its 

 length in most species ; in a few, however, the posterior part narrows somewhat 

 gradually instead of suddenly. The absolute length of the pharynx varies, speaking 

 roughly, from 30/t to 60/x, the smaller species, as a rule, possessing a smaller pharynx, 

 but not by any means proportionately smaller. M. digiturus, for instance, notwith- 

 standing that it is only half as large as M. longicaudatus, has a pharynx quite as 

 large as that of the latter. In form the pharynx varies between triquetrous and 

 hexagonal, usually three and sometimes all of its edges being clearly indicated by 

 longitudinal more or less curved chitinous ribs. A dorsal tooth seems aKvays to be 

 present, though it is occasionally inconspicuous. It is usually situated near the 

 middle of the dorsal side of the pharyngeal cavity and projects forward and inward, 

 often so much as to be very conspicuous. A few species possess ventral submedian 

 teeth, rivalling the dorsal in size, and placed on a par with it ; probably these 

 submedian teeth exist in a more or less rudimentary condition in most of the species, 

 but have been overlooked and hence left unnoticed by the authors. Portions of the 

 chitinous walls of the pharynx are covered with minute teeth or roughnesses, 

 resembling sometimes those of a rasp (first noticed by Dujardin) and sometimes those 

 of a mill-saw file (first noticed by Blitschli). These rasp-like or file-like roughnesses 

 appear to have a definite relation to the form of the pharynx, and to have a definite 

 function, namely, to aid in mastication. I have observed that the species possessing 

 rasp-like roughnesses have them placed in opposition to the projecting part of the 

 dorsal tooth, the areas covered by the minute teeth beginning near the lateral lines 

 and extending toward the ventral part of the pharynx, where the teeth seem less 

 developed than at the sides ; the dorsal surface of the pharynx near the dorsal tooth 

 is quite smooth. The species observed by me possessing plain transverse striations 

 resembling the teeth of a mill-saw file, are species in which the dorsal tooth is 

 rudimentary and situated near the base of the pharynx, the position of the striations, 

 however, being precisely that of the above-described bands of rasp-like teeth ; the 

 walls of the pharynx are, moreover, in this case traversed by certain curved transverse 

 ridges of such a complicated nature that even after considerable study of them I can 



