16 Cobb — Nematodes, mostly Australian and Fijian. 



forms a shoulder in the cardiac region. Eye spots are unknown in the genus. 

 The obUque nerve-ring encircles the oesophagus just behind the median bulb. The 

 ventral excretory pore lies somewhat behind the nerve-ring. Lateral organs have 

 been observed in but few of the species but this is doubtless due to insufficient care in 

 observation; no doubt they exist in all the species. Where they have been observed 

 they have been found to be placed opposite the pharynx and to be more or less elon- 

 gated or elhptical in form and to have their long diameter placed longitudinally. 

 In one species a glandular organ seems to exist in the oesophagus and to empty in the 

 neighbourhood of the dorsal tooth. The intestine is usually thin-walled and ends in 

 a rectum of the usual conoid form. 



The female sexual organs are usually double, symmetrical and reflexed, but 

 in two species are single and reflexed. The tail is invariably conoid and is usually 

 exceedingly slender in its posterior part. Caudal glands of the usual form are 

 absent, there being no terminal pore or spinneret. There are, however, on the 

 tail of both sexes, commonly in front of its middle point, two lateral pores, one 

 on either side, which are in my opinion the outlet of unicellular glands situated 

 near the anus. These pores and glands exist also in the genus Rhabditis. 

 Whether they are the morphological equivalents of the tail-glands in other genera 

 I am not certain. It would seem that they cannot at any rate serve the same 

 purpose as the ordinary arrangement as exhibited in Plectus and many other 

 genera. The male has but one testicle, which is invariably reflexed near the 

 extremity. The two arcuate spicula are equal in size and are elongated or linear 

 and generally acute. Their proximal ends are usually cephalated by expansion ; 

 accessory pieces parallel to the spicula are usually present. The pecuhar papillae 

 found on the tail of the male are divided into three groups of three each, a grouping 

 first made plain through the observations of Dr. Btitschh. The full complement of 

 papillae is not always present, or at least has not always been made out ; when how- 

 ever one or more pairs are absent, their position appears simply to stand vacant, and 

 their absence does not much afiect the position of those remaining. The first group 

 may be described as the pre-anal group, and its members are ventrally submedian, or 

 the posterior one may be lateral ; they are situated opposite to, or in the neighbour- 

 hood of, the spicula. The second group is post-anal and the members of it are often 

 more widely separated than those of the pre-anal group, the anterior pair being 

 usually ventrally submedian or even subdorsal. The posterior pair of the second 

 ^roup frequently lies farther back than the papillae of the third group. The latter, 

 also post-anal, are placed close together on the submedian Hne near where the tail 

 diminishes most rapidly in size. In shape the papiUge resemble hairs, and, in fact, 

 may be such, but with a special function. Those of the third group, however, 

 are different, being often more like ordinary papiUse in structure. No other 



