MONHYSTRIUM, ASYMMETBELLA 



287 



beginning some distance in front of the anus and extending on to the tail to a 

 point opposite the posterior caudal gland. Most of the papillae described occur 

 on the ventral surface of these welt-like elevations. A cross-section taken near 

 the anus clearly discloses these well-developed organs. The ejaculatory duct is 

 one-fourth, the vas deferens one-fourth, the testis two-thirds, as wide as the 

 corresponding portion of the body. Toward its blind end, however, the testis 

 tapers so as to be only one-eighth as wide as the corresponding portion of the 

 body. Spermatocytes, occupying a considerable portion of the length of the 

 testis, are one-half to two-thirds as wide as the body, so that the testis bears 

 considerable resemblance to an ovary. The/inset hblbsubm pfllb set lot setsdm 

 deceptive appearance created by these large 

 spermatocytes might easily lead to the con-nrpffl/ 

 elusion that the males are hermaphrodites. 



Habitat: Found with the preceding. 



One is inclined to suggest that this Mon- .. 



hystrium also represents a transitional form 

 from a free-living to a parasitic condition. 

 A careful study of such forms is destined to 

 throw much light on the relationship between 

 the Laimia and Alaimia. 



Although bearing considerable resemblance 

 to Monhystera, this species and its close rela- 

 tive just described seem to make a new genus 

 desirable for their reception. The distin- 

 guishing differences may be listed as follows: 

 (1) In Monhystrium, the pharynx is a double 

 chamber; moreover, the anterior chamber 

 has a distinctly radiated structure, more eas- 

 ily seen if the specimen is viewed slightly 

 obliquely instead of laterally, as shown in the 

 illustration. These radial elements are stiff- 

 ening factors enabling the lips to bite more 

 efficiently. The margins of the lips are sharp- 

 cutting edges, as is clearly shown in the profile 

 view in the illustration. Further study is necessary to determine whether these 

 organs are odontia or onchia. (2) The pseudo-bulb, which is not common in 

 Monhystera. (3) Monhystrium is ovoviviparous or viviparous. (4) There is 

 a pronounced renette. (5) There are no cephalic setae or the setae are very 

 weakly developed. (6) The species is presumably carnivorous; the more typical 

 Monhysteras, perhaps all, are vegetarian. 



Larvae removed fron the uterus of alcoholic specimens present differences 

 from the adults as follows: (1) The amphids are farther back. (2) The pharynx 

 is tubular, and not in two parts. (3) The head is more tapering. (4) The spin- 

 neret is not so well defined. (5) No wings were seen. (6) The pseudo-bulb is 

 less conspicuous. Fig. 696, on this page. Syn. Monhystera wilsoni Baylis. 



1.3 14. 27. '"'62'" 95- >2 



70. Asymmetrella glabra n. sp. U4 *- 6 E - 3 1 - 8 '' ' " Lips three, dis- 

 tinct, unequal, flat, thin. Pharynx with a peculiar dorsal onchium, bent inward 

 at right angles at the apex. Oesophagus surrounding the posterior two-fifths of 

 the pharynx in the form of three, somewhat finger-shaped processes. Wall of 

 the pharynx fairly well cutinized, especially near the lips on the dorsal side, 



