ABT. 10. PARASITIC BOUND WORMS OF THE RABBIT — CHANDLER. 3 



and position of vulva, and distinctly falls into the filicoUis group as 

 described by May (1920). The male differs, however, in the form of 

 the tip of the spicules, in the shape of the bursa, in details of the 

 arrangement and relative size of the bursal rays, in the number and 

 arrangement of bosses, and in the thickness of the body. The female 

 differs in its more slender body, the greater length of the tail, and in 

 the more posterior position of the vulva. The latter characteristic is 

 sufficient to distinguish the females from any other species of the 

 genus. In this respect it approaches the genus Mecistocimts, but 

 does not approach it at all, as do some other species, in length of 

 spicules, size of eggs, or presence of cervical papillae. This still 

 further bears out May's (1920) contention that Mecistocii'^i'its is not 

 justifiably separated from Nematodiru^. 



OBELISCUS CUNICULI GraybiU (1923). 



Plate 2, figs. 6-11. 



Since tlie original draft of this paper was written, the description 

 of this worm by GraybiU (1923), as a new genus and species, has 

 appeared. It seems desirable, however, to add a few details to 

 GraybilFs description. 



The worms are relatively large and robust for Trichostrongylids. 

 GraybiU describes them as whitish in color with some dark streaking 

 due to the color of the intestine, but when living, in a freshlj' 

 opened stomach, the worms are blood red in color. The long-itudinal 

 cuticular ridges vary in number from 16 to 26 in males and from 36 

 to 40 in females. These ridges are broken by transverse indentations 

 at intervals of about 200 |x in the anterior portion of the female, and 

 at somewhat shorter and more irregular inteiwals in the male. Ex- 

 tremely fine and inconspicuous transverse striations are present, 

 most evident in the region of the vulva and on the tail of the female. 

 The nerve ring crosses the esophagus a little anterior to the middle 

 of it-s length. 



The bursa (fig. 7), as mentioned by GraybiU, consists of two large 

 rounded lateral lobes, separated from each other dorsally by a 

 relatively small dorsal lobe. At the obtuse angles fonned where 

 the ventral rays on the one hand, and the medio and postero lateral 

 rays on the other, terminate near their margins, the bursal lobes 

 have a maximum width of about 400 to 450 pi, while their maximum 

 length, measured to the point where the extemo-lateral ray ter- 

 minates, is about 500 to 600 [jl. The entire ventral surface of the 

 1)ursa, except a fluted margin about 40 [x in width, is thickly covered 

 with dew-drop-like bosses, giving the bursa a beautifulh^ sculptured 

 appearance. The ventro-ventral ray is smaller than any of the 

 other rajs in the lateral lobes except the externo-dorsal. The latero- 



