16 



THE ROUNDWORMS OF DOMESTIC SWINfi. 



uniform, about 95 fi. The posterior ovary, much convoluted, fills 

 most of the space between the anus and the terminus of the posterior 

 uterus (fig. 4). The ovaries are long filiform tubes, 34 /j. in diameter 

 in their narrowest part. The thick-shelled eggs are covered with a 

 thin irregular membrane resembling the albuminous membrane of an 

 ascarid egg. Under high power a faint line at either pole can be 

 seen running transversely through the thickness of the shell, sug- 

 gesting an operculum. The embryo is surrounded by a thin envel- 

 ope, differentiated from the shell by its greater translucence and 

 lack of granulation (fig. 6). Most of the eggs in the uterus contain 

 well-developed embryos, but a few near the ovaries appear in the 



morula stage. The shell, including 

 the translucent membrane surround- 

 ing the embryo, is 4 // thick, the 

 embryo occupying a space 11 // by 

 24//. 



The general appearance of the two 

 sexes is represented in figures 10 

 and 11. 



The first specimens of Arduenna 

 strongylina were collected by Bremser 

 and figured by him in his Icones 

 Helminthum (Bremser 1824c). They 

 were first described, however, by 

 Rudolphi (1819a, p. 237). His de- 

 scription may be freely translated as 

 follows.: 



Head slender, continuous, mouth orbicular, 

 body somewhat attenuated anteriorly, tail of 

 male coiled either in a single spiral or in a 

 spiral and a half. A broad wing extending 

 on either side of the tail. Spicule very long. 

 Apex of the tail very short, naked. Apex of 

 the tail of the female depressed, straight, 

 subacute. 



In a preliminary note Rudolphi (1819a) gives the measurement of 

 the males as about 5 lines long (=10.6 mm.) and the females as 7 

 lines long ( = 14.9 mm.). 



Gurlt (183 la) is the first on record to collect the worm from domes- 

 tic swine. His description of the anatomy of Spiroptera strongylina 

 follows Rudolphi's, but contains also the statement that the vulva 

 is situated a short distance in front of the anus. He describes the 

 mouth as smooth, without papillae. Subsequently (Gurlt, 1847a) he 

 added to his description a note on the anatomy of the pharynx, the 

 first reference to this structure, which he describes as banded by two 

 spiral muscles (a misinterpretation of the spiral chitinous ridges of 



FIG. 11 .A rduenna strongylina. General view 

 of body of female from left side, a., anus; 

 ut., uterus; v., location of vulva. X 7.5. 

 (Original.) 



