326 proceedings of section d. 



General External Characters. 



The specimens of this worm which we have examined show 

 great variations in several details, especially in the female, though 

 this does not appear to have been noticed by previous writers. 

 The variations met with in three typical males and six typical 

 females are recorded in the accompanying table. One or two of 

 these may be due to differences in age of the worm, or in the amount 

 of ante and post-mortem contraction ; but it is obvious on con- 

 sideration that all cannot be the result of such factors. 



Length of male 



Diameter, anterior end, 0. 15 mm 



Diameter, middle of length 



Diameter, 0.5 mm. from anterior end 



Diameter, level of male opening 



Excretory pore from anterior end 



Nerve ring from anterior end 



Cardia from anterior end 



Cardia — length . . 

 — diameter 



CEsophagus — length . . 

 — diameter 



Cloacal opening from tip of tail 



ilong 

 ( short 

 (long 

 \ short 



Spicules — length 



— diameter 



Range. 



cm. 

 3.8-5.3 

 mm. mm. 

 .052 -.062 

 .141 -.151 

 .069 -.082 

 .042 -.051 

 .251 

 .172 -.188 



.65 -.72 

 .0155 



.048 -.062 

 .148 -.155 

 .078 -.094 

 .0078-.010 

 .0061-.0078 



