161 



SCLEROSTOMA HYPOSTOMUM, Dujarclin. 



Plate XXIII. 



Description. — Male, IG'"™ ; female, 24""". Body white, cylindrical, and stout. Head, 

 globular, a little ventrally curved and truncate at the moutli ; bead papilke six; 

 neck papillie not observed; ventral cleft about opposite the end of the second fifth 

 of the ccsophagus, couuting from the head. Uuicellulai glands and lateral lines very 

 conspicuous. Mouth-opening round, obliquely inclined; surrounded by a single 

 circle of very minute saw-like teeth. The globular chitinous capsule is marked by 

 numerous longitudinal elevations, which are stronger at its bottom. The posterior 

 opening is circular, unarmed, but roughened. Around the mouth is a circular caual 

 which empties into a dorsal canal. There is apparently no pharyngeal apparatus as 

 in Dochmiiis. ffisophagus slightly swollen caudally. Two lateral ducts opening near 

 the mouth and situated on either side of the head are apparent ; they seem to end 

 caudally in the lateral canals. Male about two-thirds the length of the female. 

 Bursa shallow, set on obliquely, campauulate. Ventral costte either separate or 

 slightly so ; lateral slightly separate if at all ; dorsal pair irregular and widely sep- 

 arate; the dorso-lateral and dorsal forms a single stem with three lateral branches. 

 Spicula l.r>"'"' long, linear aculeate, cross-striated, and bordered by narrow margins 

 whicli roil in towards each other. Two anal papilhe. Female stout and thick, and 

 usually with a brown crust near the vulva. Vulva very near the tail. Tail full to 

 near the end, but ending in an acute mucronate point. Uteri directed toward the 

 head ; one, the caudal, makes a loop at the tail. The ovaries show loops near the 

 tail. Eggs elliptical, 0.1'""' long, O.OG""" broad, laid in the gastrula stage. Embryo 

 not observed. 



Occurrence. — Sclerostomahi/postomum is fonTul iu tbe large intestine 

 of ruminants. It is present associated with (Eso])hagostoma Goliim- 

 hianum in sheep in this country, but not abundantly. It is closely re- 

 lated to Sclerostoma equinum of horses, a species said to make tumors 

 in tbe intestines. As S. hypostomum is rare, it has not yet been deter- 

 mined whether it causes intestinal tumors in sheep. Since S. tetracan- 

 thuni, whose embryos make tumors iu the ca)cum of the horse, is more 

 nearly related generically to QiJso^fhagostoina than to Sclerostonia, I am 

 inclined to believe, as I have proven in regard to (Esophagostoma Golum- 

 bianum in sheep, that the species belonging to tbe genus GEsophagostoraa 

 are intestinal — tumor-making parasites rather than those of Scleros- 

 toma. 



Life history.— M. Baillet {Nouveau Diet, de Med. T. VIII, art. Hel- 

 minthes, 1886) is authority for the following: 



The sclerostome of ruiuiuauts is reproduced in tiie same way as that of solipeds. 

 Its eggs, of which the vitoUus is segmented in the uterus of tlie feiiuile, are laid in 

 the large intestine and carrietl without by the fecal material. TLey are hatched after 

 23038 A p 11 



