Intestinal Trematodes and Nematodes in Dogs. 321 



Prevention. As the ascaris develops in the bowel directly from 

 the ovum or embryo taken in with food or water, every effort 

 must be made to prevent its admission by these channels. Ponds 

 and streams that receive drainage from the droppings of affected 

 dogs (kennels), and wells in porous soils which receive surface 

 seepage should be avoided as far as possible, and the water from 

 such given only after it has been boiled. Even the vomited mat- 

 ter, charged as it may be with the ascarides and their eggs may 

 be discharged into drinking water or feeding vessels, and infest 

 other animals as well as the one that furnished it. The frequent 

 washing and scalding of feeding dishes is therefore no less impor- 

 tant than the expulsion of the worms from dogs that live in the 

 same place. 



Oxyuris Vermicularis. Zurn claims to have found this 

 parasite of man in a dog but as no one else has, there is a strong 

 probability of error. In any case it must be extremely rare. 



UncinariaTrigonocephala. U.Canina. AnchylostomaT. 

 Dochmius T. White body abruptly narrowed near the head 

 and bent (hooked) upward. Male 9 mm. to 12 mm. long, with 

 trilobate caudal membrane, the middle lobe, the smallest. Female 

 9 mm. to 21 mm. long, tail obtuse with a mucron or sharp pro- 

 cess, vulva toward the posterior third of the body. Mouth round 

 with buccal capsule furnished ventro-laterally on each side with 

 a hard chitinous curved jaw, terminating in three strong sharp 

 teeth turned inward and backward ; two smaller teeth project 

 downward from the dorsal border. Eggs ovoid 74/* to 84/* long, 

 by 48 /x. to 54 ju. broad. 



Habitat. Small intestine of dog and fox, in company with 

 the U. Stenocephala. 



UncinariaStenocephala. Anchylostoma S. Dochmius S. 

 This worm is smaller than the above species : Male 6 mm. to 

 8 mm. long, with same form of caudal membrane : Female 8 mm. 

 to 10 mm. long, with the same acute prolongation on the tail, 

 and the vulva in its posterior third. The mouth differs strikingly ; 

 the head is small and the buccal capsule constricted, with a 

 ventral chitinous fold and sharp border covering one sharp tooth. 

 The dorsal border has a median depression but no distinct tooth. 

 Eggs ovoid, 63 /x to 67 /u long, by 32 /a to 38 jix broad. 



Pathogenesis. Habitat. This occupies the small intestine in 

 21 



