2 PKOCEEDIXGS OF THE NATIONAL MUSEUM. vol.66. 



unusual condition in the genus. Dorsal lobes of bursa set otf from 

 latei'al lobes by a distinct notch and separated from each other by a 

 shallow indentation. Dorsal ray moderately stout, bifurcated to 

 about one-fourth its length from the tij) of the longest prong. Ex- 

 terno-dorsal rays long and ver}^ slender, about midway between 

 dorsal ray and postero-lateral ray. Postero-lateral and medio-lateral 

 rays close together, arising from a common trunk, and extending 

 almost to the margin of the bursa. Externo-lateral ray stout, cui*v- 

 ing sharply away from other lateral rays in its distal third, and 

 ending at some distance from the bursal margin. Latero-ventral 

 and vent ro- ventral rays in contact for their whole length, curved for- 

 ward, and ending at some distance from the bursal margin. These 

 rays are much more slender than the lateral rays, but mucli thicker 

 than the doreal ray. Their length is only about half that of the 

 externo-lateral and medio-lateral pair. Bosses numerous and small, 

 occupying the portion of the bursa from near the ventral margin 

 to the externo-lateral and medio-lateral pair of rays. Spicules (figs. 

 4^5) deep brownish red in color, 0.65 to 1.05 mm. long, united for 

 the greater part of their length, and showing distinct striations on 

 the proximal half. Tip of spicule curved ventrally, and ending in 

 a membranous bulb. A pair of membranous wing-like expansions 

 occur along the ventral side distally, ending in obtuse angles just 

 proximal to the bulb. These membranous expansions have very fine 

 markings as shoAvn in figure 5. The body of the spicule ends in a 

 finger-like process bent sharply dorsal, and ending on the dorsal 

 margin of the bulb. 



Female 16.5 to 20 mm. in length, with a maximum diameter of 

 180 to 220 [L at the vulva. Diameter abruptly but moderately reduced 

 behind vulva. Head diameter 35 to 40 [a, exclusive of inflated cuticle : 

 latter well developed, usually markedly asymmetrical, conspicuously 

 striated, reaching a diameter of from 55 to 75 \i. and extending back 

 on the neck to a point 130 to 145 jx from the anterior end. Esophagus 

 450 to 600 [JL in length. Tip of tail truncated and provided with the 

 usual bristle-like process. Anus 105 to 115 [i from truncated end of 

 body. Vulva a transveree slit 420 to 486 pi, almost exactly one-fourth 

 length of body, from posterior end. Eggs long oval, measuring 160 

 to 180 PL by 80 to 90 pi, in various stages of development from morula 

 to fully formed eml)rY() when deposited. 



Host. — Domestic rabbit, Oryctolagus cuniculus. 



Location. — Duodenum. 



Locality. — Houston, Texas. 



Type. — Male, U.S.N.M., Helm. Coll. 7733; paratypes, males and 

 females, U.S.N.M., Helm. Coll. 7734. 



This species of Nematodirvs seems to come closest to flicoUis, 

 which it resembles in general bursal characteristics, short spicules. 



