22 



THE ROUNDWORMS OF DOMESTIC SWINE. 



to 315 p long by 53 p wide, furnished with a spiral band which usually breaks up into 

 separate rings in the middle of its course and resumes the spiral toward the posterior 

 end. The number of turns to the spiral varies between 21 and 25. There is a cervical 

 papilla on the left side, 281 ft from the anterior end. The excretory pore opens on the 

 right side, 526 p from the anterior end. The lateral cuticular wings, 3 on each side, 

 commencing at the base of the cephalic cuticular inflation, extend posteriorly for a 

 distance about one-third of the body length. The middle wing of each three is 00 p 



wide at its middle, the point of 

 greatest width. The other wings 

 are about half as wide (fig. 18). 



Male, 6 to 9 mm. long, measured 

 in a straight line. Body nearly 

 uniform in diameter, averaging 

 263 ft, and attaining ite greatest 

 width of 315 p at the point of the 

 greatest width of the lateral 

 wings. The narrow bursal mem- 

 branes, about half the width of 

 the body, extend from a point 

 about 1.4 or 1.5 mm. from the 

 caudal extremity, to and includ- 

 ing the bluntly pointed tip (fig. 

 19). Caudal extremity twisted 

 into a fairly regular spiral, having 

 usually three turns. Long spicule 

 grooved on the ventral side, 2.1 

 to 2.25 mm. in length, or five to 

 six times the length of the short 

 spicule, very slender, gradually 

 tapering to a fine needle point. 

 Short spicule 300 to 350 p long, 

 relatively broad at its base, sud- 

 denly tapering to a fine point. 

 The ventral surface of the short 

 spicule is provided with a narrow 

 wing extending nearly to the tip. 

 Bursa furnished with eight pairs 

 of papillae (fig. 20). Of these the 

 four pairs of preanal papillae are 

 long and stalked; the postanal 

 papillae, close to the tip of the tail, 

 are very small, with short stalks. 

 Female 13 to 19 mm. long, 

 average about 16 or 17 mm. Maximum width 333 to 450 p in the region directly 

 anterior of the anus. The body rapidly increases in diameter from the anterior 

 end to the region of greatest width of the lateral cuticular wings. At this point 

 the diameter is nearly as great as in the region of the anus. It then rapidly 

 diminishes to half as much at the end of the first third of the body; then slowly 

 increasing, it reaches a maximum near the anus and abruptly diminishes, the 

 body ending in a blunt point furnished with a mucronate tip. Anus 120 p from the 

 caudal end, 50 p in diameter (fig. 21). Vulva posterior of the middle, 35 p in diam- 

 eter, dividing the body in the ratio of 9 to 8. The vagina extends posteriorly (fig. 22). 

 Uterus bilobed, the ovaries lying at opposite extremities. Eggs 34 by 15 ft, slightly 

 flattened at the poles. Embryo well developed before oviposition (fig. 23). 



lo.mm. 



FIG. 18. Physocephalus sexalatus. Dorsal view of anterior 

 end of body. c. cut. inf., cephalic cuticular inflation; c. p., 

 cervical papilla; ., esophagus; ex. p., excretory pore; lab. p., 

 labial papillae; I. c. to., lateral cuticular wings; n. r., nerve 

 ring; ph., pharynx. X 150. (Original.) 



