206 



FILTER-BED NEMAS 



syngonic or digonic. Such observations as I have been able to make upon 

 glycerine specimens of obtusus lead me to conclude that this species at least 

 is probably digonic; if it is syngonic we are confronted with the phenomenon 

 of the ovary first acting as a testis and sending over into the rudimentary 

 posterior part spermatocytes, probably primary spermatocytes, there to con- 

 tinue their development. 



9. Cylindrolaimus obtusus Cobb. 



- 58? 

 3.5 



Fig. 8 Cyl- 

 indrolaimus 



2.6 3.3 3.5 Z.8 ' 



The moderately thin cuticle 

 is traversed by five to six hun- 

 dred transverse striae, which do 

 not appear to be further resolv- 

 able. In glycerine specimens 

 there are very faint indications 

 of longitudinal striations, which 

 are more pronounced toward the 

 anterior extremity; these may be 

 due merely to the attachments of 

 the somatic muscles. There ap- 

 pear to be no very distinct lips, 

 though probably minute lips are 

 present, so small and so closely 

 amalgamated as easily to escape 

 observation. Occasionally six 

 excessively minute papillae have 

 been seen immediately round the 

 mouth opening; though no doubt 

 always present, these papillae 

 usually escape observation. 

 When the lips are closed the 

 small mouth opening appears as 

 a simple pore in the middle of 

 the front of the head, where 

 there is an exceedingly minute 

 depression. Four submedian, 

 somewhat papilla-like, widely- 

 spreading cephalic setae occur 

 on the margin of the head about 

 half way between the anterior 

 extremity and the front of the 

 amphids; each of these setae is 

 about one-fourth as long as the corresponding diameter of the head. The 

 well-developed lateral fields are about one-third as wide as the body. There 

 do not appear to be any distinct wings. 



Intestine. Ovary. The somewhat cylindroid cardia is of relatively large 

 size, and is separated from the oesophagus by a constriction; it is about two- 

 fifths as wide as the base of the neck, and is surrounded by about seven uni- 

 cellular organs, probably glandular in nature. There is a small posterior branch 

 of the sexual apparatus, extending backward a distance about equal to the length 

 of the body diameter, serving either as a testis or spermatheca, apparently the 

 former. The ellipsoidal, thin-shelled, smooth eggs are five-sixths as wide as 



X675 



