THE MONONCHS 1 



(Mononchus Bastian 1866) 

 A GENUS OF FREE-LIVING PREDATORY NEMATODES 



CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY VI 



(With 75 illustrations in the text) 2 



BY 



N. A. COBB 



INTRODUCTION 



Mononchs are Predaceous 



No free-living nematodes have gained more in interest during recent 

 years than those constituting the genus Mononchus; this is because the 

 latest discoveries have led to a complete change of view concerning their 

 economic relationships. Careful examination, here recorded, of a large 

 number of specimens belonging to many different species of Mononchus, 

 has fully demonstrated the predaceous character of certain common and 

 widely spread soil-inhabiting species which are found to feed on other 

 small animal organisms, such as protozoa and rotifers, and, most interest- 



1 Reprinted from Soil Science, May, 1917, with renumbering of pages and errata, (p. 184). 



2 For the most part the illustrations were prepared under the author's personal supervision by 

 Mr. W. E. Chambers of the Bureau of Plant Industry. Many features set forth in them cannot 

 be seen in the natural object except with the aid of the best immersion lenses skillfully used 

 under favorable conditions. Frequently no further allusion is made to facts thus elucidated . So, 

 too, information contained in the key may not be repeated elsewhere; the key should therefore be 

 consulted in connection with each description. Most of the illustrations are original; when not 

 so, their source is indicated. The species figures are all at the same magnification, so that the 

 reader may judge of the relative sizes of the nemas. Explanatory abbreviations follow. 



amp ampulla 

 amph amphid 

 an anus 

 an gl anal gland 

 ar dnt denticula 



cav som body cavity 



cl int intestinal cell 



cl msc muscle cell 



cl nrv nerve cell 



cl nrv subm submedian nerve 

 cell 



col crd cardiac collum 



crd cardia 



cst ph pharyngeal rib 



cut cuticle 



dct duct 



dct gl cdl duct of one of the 

 caudal glands 



dnt denticules 



fix ovr post flexure of poster- 

 ior ovary 



gl gland 



gl an anal gland 



gl cdl caudal gland 



gl oe cesophageal gland 



grn granule 



gl sal salivary gland 



ing ingested material 



ing nematod ingested nema- 

 tode 



int intestine 



inc iunction 



lam Ib labial lamina 



Ib lips 



lum int lumen of intestine 



lum oe lumen of oesophagus 



lum som body cavity 



ms an anal muscle 



msc oe cesophageal muscle 



msc som body muscle 

 mur ex external wall 



mur int intestinal wall 



mur ph pharyngeal wall 



mur ut wall of uterus 



ncl nucleus 



ncl cl int nucleus of intesti- 

 nal cell 



ncl lat lateral nucleus 



ncl ov nucleus of ovum 



nrv nerve 



nrv r nerver ring 



oe oesophagus 



oes lum oesophageal lumen 



on dsl dorsal tooth . 



on rtr dsl retrorse dorsal 

 tooth 



on rtr subm retrorse submed- 

 ian tooth 



on subm dxt right submedian 

 tooth 



on subm snst left submedian 

 tooth 



org orgnn 



ov ovum 



ov dct oviduct 



ov frt fertilized esrg 



(S. S.431) 129 



ov im immature egg 



p ex excretory pore 



ph str pharyngeal striae 



por pore 



por gl oe pore of oeeophageal 

 gland 



ppl papilla 



ppl cdl caudal papilla 



ppl intr interior papilla 



ppl Ib labial papilla 



ppl Ib extr exterior labial 

 papilla 



ppl subm submedian papilla 



opl subm sec secondary sub- 

 median papilla 



ppl trm terminal papilla 



rcpt sem seminal receptacle 



ret rectum 



reg vnt ventral field 



set seta 



spm spermatozoa 



spn spinneret 



str mur ph striae of pharyn- 

 treal wall 



subcut subcuticle 



sut Ib labial suture 



teg ov egg shell 



trm ovr Wind en-l of ovnrv 



ut utenis 



vag vagina 



vagmsc vaginal muscle 



vlv vulva 



