468 ARABIAN NEMATODES. 



equal and arcuate. They are one and one half times as long as 

 the anal diameter and not of uniform breadth, presenting notice- 

 able irregularities. Their proximal ends are not cephaloid. The 

 two lamelliform accessory pieces are two thirds as long as the 

 spicula. The single testicle, one half as wide as the body, and 

 hardly as long as the oesophagus, is directed forwards, only its free 

 extremity being reflexed. In its anterior fourth are found the 

 mother-cells of the spermatozoa. Their diameter nearly equals 

 the width of two of the striae of the cuticula. These mother-cells 

 are granular and stain strongly. In the succeeding fourth of the 

 testicle the mother-cells give rise to the true spermatozoa which 

 fill the posterior half of the testicle. These are spherical cells 

 whose diameter is slightly greater than the width of one of the 

 striae, and whose nuclei only can be stained, at least with carmine. 

 It will be seen that this organ has a double function. It is at 

 once testicle and vas-deferens. The ductus ejaculatorius is com- 

 posed of two rows of cells, the first ten or twelve pairs being 

 larger than the others and of a diflferent structure. 



Hah. — Found among algae and in the sand at their roots on 

 the coasts of Arabia and Ceylon. The males were mature in 

 February. 



