460 ARABIAN NEMATODES, 



will be seen that these four organs are not very symmetrically 

 placed. In other respects however they are much alike. Each is 

 an ellipsoidal unicellular body about one third as wide as the 

 adjacent part of the oesophagus and two thirds as wide as long. 

 Each has one nucleolated nucleus lying in the midst of the granular 

 contents, and each is connected from its anterior portion with the 

 exterior by an exceedingly fine but perfectly distinct short duct 

 which passes quite through the cuticula. The interpretation 

 which these structui'es seem to call for is this : Each is a uni- 

 cellular oland. I must however relate certain circumstances 

 which cause me to be doubtful about the completeness of my 

 observations. In the first place I have thus far observed these 

 organs distinctly in one specimen only, a young female. In this 

 specimen however they are so perfectly stained by carmine as to 

 be extremely conspicuous. No other among the half dozen of this 

 species in my Aden collection permits me to see these organs very 

 plainly. Nevertheless I can see one or more in all of them more 

 or less distinctly, and do not doubt the existence of at least four 

 in each. I cannot tell why only one individual out of a half 

 dozen of the same species treated alike should alone have taken 

 the stain so as to show these organs. In the second place, there- 

 fore, I cannot be certain that not more than four of these organs 

 exist in each individual ; for of course the same circumstances 

 which caused the one individual alone to so stain as to show these 

 organs may in a like manner have caused only part of the organs 

 in that individual itself to have taken the stain, but I do not 

 think this veiy probable. After a careful search I have failed to 

 discover more than the four, but I must add that I have made 

 observations on species of other genera which make me believe 

 that a series of latei'al organs, each connected with the exterior, 

 sometimes extends throughout the length of the worm. It only 

 remains to add to this rather lengthy description of these four 

 organs that they are quite distinct from each other. 



The female sexual apparatus is asymmetrical. From the rather 

 inconspicuous vulva the muscular vagina leads forward into the 

 uterus, which commonly contains one to four eggs, each having a 



