FOOD HABITS OF MOXHYSTERA 



205 



MONHYSTERA Bastian 1865 



M. subfiliformis n. sp. 



2./ 2. 



This form, which appears to be new, is closely 

 related to Monhystera filiformis Bastian, but dif- 

 fers from the descriptions given by various authors 

 in the following respects: There are 10 cephalic 

 setae on subfiliformis instead of six. The am- 

 phids are somewhat larger than given by most 

 authors for filiformis. In the cardiac region I 

 have noticed in the single specimen of the present 

 species so far examined, a very definite pseudo- 

 bulb. There is a definite renette, as shown in the 

 figure, with an excretory pore opposite the nerve 

 ring. The eggs are relatively larger than de- 

 scribed for filiformis. The anatomical details are 

 clearly shown in Fig. 7. This species also shows 

 a certain amount of resemblance to Monhystera 

 vulgaris, de Man, but differs in having setae on 

 the body, and in having 10 cephalic setae, and in 

 the amphids being slightly different in position, 

 form and size. The tail of vulgaris also seems to 

 be more slender. 



Habitat: Sand, Washington filter beds; j|/^Jf 

 usually uncommon. Of the numerous ^ . 

 species of Monhystera I have had occa- Uncm- 

 sion to examine with respect to their 

 food habits, all appear to be largely if 

 not wholly vegetarian. The various spe- 

 cies specialize to a considerable degree in 

 the matter of food. For instance, many 

 marine species feed almost exclusively 

 on diatoms. If the filterbed Monhysteras 

 are not an exception to the rule, they 

 would seem to be dependent on fungi and 

 bacteria as a source of food, except in 

 open beds, where of course they would 

 find an abundance of green microphytes. 



CYLINDROLAIMUS de Man 1884 



Sexual Organs. Cylindrolaimus typi- 

 cally has but a single outstretched ovary; 

 from the observations of various authors 

 it would appear that this may extend 

 either forward or backward, usually for- 

 ward. As there is some doubt about the 

 shape of the organ in the type species 

 communis, it is desirable that specimens 

 of that species be reexamined. Inasmuch 

 as the male of only one of the six true 

 species of Cylindrolaimus has been seen, it 

 would seem that the genus is typically 



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