A Nematode Formula. 



a pharynx wliieli is about half as wide as deep and which is armed \dt\i 

 three teeth, two sub-equal ones reaching half-way to the lips, and a third, 

 the left submedian, stouter and half as long again. Passing the pharynx, 

 the food enters an oesophagus which is in its anterior part less, but in its 

 posterior part more, than half as wide as the neck. Passing then through the 

 rather large cardia, it enters the intestine, whose commencement is indicated 

 by a distinct but shallow cardiac collum. This moderately thin-walled 

 intestine is composed of a single layer of cells, of which about fifteen side by 

 side make up the circumference, and terminates posteriorly in a rectum 

 whose length is hardly greater than that of the anal diameter. A sac- 

 shaped unicellular ventral gland, as long as the body is wide, lying nearly as 

 far behind the cardia as the slightly oblique nerve-ring is in front of it, 

 empties, by means of a long narrow duct and a distinct narrow-necked 

 ellipsoidal ampulla, through the porus excretorius, situated about as far 

 behind the base of the pharynx as the latter is behind the lips. The lateral 

 fields are about half as wide as the body. They are usually conspicuous at 

 both extremities, but especially the posterior, through the presence iu them 

 of numerous pigment granules. The narrow median fields, one-ninth as 

 wide as the body, are much less readily distinguished. The tail of the female 

 is conical to its somewhat clavate posterior third. It presents a slightly 

 swollen terminus having a conical outlet for the three caudal glands, the 

 most remote of which Hes near the commencement of the posterior fifth of 

 the body. Three or four thin-shelled, oblate, unsegmented eggs, as long as 

 the body is wide, are usually to be seen lying in the uterus near the rather 

 inconspicuous vulva. Small one-celled glands encircle the very short vagina. 

 The multicellular, bilaterally-symmetrical organ discovered by De Man is 

 situated between the vulva and anus. 



'■■i- The male tail narrows gradually from opposite 



the proximal ends of the spicula, becoming at the anus suddenly finger-shaped 

 by diminishing abruptly on the ventral side. The finger-shaped portion has 

 a diameter one-half as great as the anal diameter, and gives to the posterior 

 extremity of the worm when seen in profile the general form of an index (^g°) . 

 Two minute, bristle-bearing, submedian papillae, pointing backward, appear 

 on each side immediately behind the anus. Opposite the posterior -third of 

 the two equal, linear, barely arcurate, pointed spicula stand yet other papilla?, 

 to the number of about six or eight, those nearest the anus being submedian, 

 but one or two of the more remote appearing to be median. The spicula, 

 when seen in profile, appear to make but a slight angle with the axis of the 

 body. They are a trifle more than one-half as long as the tail, or a little 

 more than twice as long as the anal diameter, are destitute of accessory pieces 

 and jDOssessed of proximee hardly to be called cephaloid. Tlie testicles join 

 the vas deferens near the middle of the body. The region occupied by the 

 ductus ejaculatorius commences at the beginning of the posterior fifth of 

 the body,, and is supplied with oblique copulatory muscles. 



Both sexes about equally common in sand and among weed along the 

 shores of Port Jackson, JN'ew South Wales, October, 1889. 



I hope by the aid of this new formula to be able to describe, even without 

 the aid of figures, at least such species as belong to already well known 

 genera, so accm^ately as to leave little to be desired, and yet so briefly as to 

 leave space for the full discussion of the important relations existing 

 between these worms and diseases of plants. 



(A Sydney : Charles Potter, Government Printer,— 1S90< 



