INTESTINAL ROUND WORMS. 



Sheep ia this country harbor at least six species of round worms, 

 parasitic iu the small and large intestines, which their ancestors brought 

 with them from Europe. They are : Strongylus filicolUs, Rud. ; Strongy- 

 lus ventricosus, Rud., both found in the duodenum ; Dochmiiis cernuus, 

 Creplin, fouud in the small intestine ; Ascaris lumbricoides, Linu., also 

 found iu the small intestine; Trichocephalus affinis, Eud., found in the 

 caecum ; Sclerostoma hypostomum, Diesing, found in the large intestine. 

 A seventh species, (Esophagostoma Gotuinbianum, Curtice, is found in 

 the large intestine and is probably indigenous to this country. Of all 

 these the last species produces by far the most injury. Dochmius cer- 

 nuus is next in importance. The injury inflicted by the others may, at 

 times, and in conjunction with other parasites, be considerable; but> 

 disease which may be ascribed to either species alone has not yet been 

 reported. From personal observations it is believed that the number 

 of individuals in each sheep are usually too few to ever cause extensive 

 loss, and that their greatest harm is from the little discomforts which 

 they may add to those produced by the more destructive parasites. 



At certain seasons of the year some of the above species are abun- 

 dant, while at other times but few individuals may be found. Strongy- 

 lus filicolUs and 8. ventricosus are usually found associated together, but 

 are so small that they can easily be overlooked, or if found may be re- 

 garded as the young of other species. Dochmius cernuus is about an 

 inch long, and being large is readily detected. Ascaris lumbricoides is 

 rare, having been met with only a few times by helminthologistsinany 

 country, and in but one lot of sheep by the author. Trichocephalus 

 affinis is usually fouud in young sheep, but is met with in comparatively 

 small numbers. Sclerostoma hypostomum seems to be a rare species in 

 the East, the single instance in which it was met with in these investi- 

 gations being in examining an old sheep in Colorado. (Esophagostoma 

 Golumbianum seems to take the place of the last-named species in the 

 Bast, and is fouud most abundantly in spring and summer in its adult 

 state, although it is present throughout the year. The most favorable 

 time for collecting most of these species has been in late fall and win- 

 ter. The quantities in which the various species may be found vary 

 with the season and the flock examined, so much so that no accurate 

 statements of percentage of occurrence or of distribution can be made. 



The symptoms which these wormsproduceare those of general dobil- 

 23038 A P 10 145 



