149 



Strongylus ventricosus, Eud. 



Plate XX. 



Description. — Male, G'"™ ; female, IS™'". Body very small and comparatively stout. 

 Males and young females usually spirally coiled; body of old female straight, with 

 cephalic end coiled. Skin transversely striate, marked by fourteen longitudinal 

 lines; the five larger standing at equal interspaces on the dorsal and ventral sur- 

 faces, the two smaller stauding close together ou the sides. The crossings of the 

 striiB and longitudinal lines make pits which are quite characteristic. Head little 

 larger than neck, but hemispherical and continuous with the cylindrical inflation of 

 the neck. No head or neck papillic visible. Mouth terminal, very small and round. 

 The end of the head is furnished with a hemispherical cap-shaped chitinoUs piece. 

 Other oral armature apparently absent. Inflated portion of head about one-fifth the 

 length of oesophagus. Unicellular glands not apparent. Male about one-half the 

 length of female ; bursa conical and bilobed, the ventral membrane being narrow, 

 the dorsal wide; ventral costoe not separate, smaller than the ventro-lateral, which 

 is stout ; lateral widely separate and apparently formed of three nearly equal costie ; 

 dorso-lateral slender ; dorsal notched at the end and giving off laterally a very short 

 side branch. Spicula O.Sti"™ long, short and stout, and margined by a fringe-bearing 

 sinuous membrane. They are tipped by a soft pad-like expansion of the membrane. 

 Female characterized by a swelling at the vulva, which gives the species its name. 

 This character is more pronounced in older specimens. Vulva from two-ninths to 

 one-third of the entire length of the female from the tail. Uteri directed anteriorly 

 and posteriorly from the vagina. Ova 0.13""' long, 0.07""" wide, comparatively 

 large, and found in all stages of segmentation. Embryo not observed. 



This species is found in association with Strongylus fiUcolUs in the 

 upper part of the small intestine of sheep. It can be separated by its 

 smaller size, its spiral twist, and the markings of the skin. It is best 

 found in fall and winter. The species was originally described from 

 specimens taken from cattle, and so far as known has never before 

 been noticed as being found in sheep. Tlie female in its adult stage re- 

 sembles the small specimens of 8. filicollis. It is apparently the cause 

 of little or no disturbance, although from the appearance of its month 

 parts it might seem to be more injurious than S. filicollis. 



