Intestinal Trematodes and Nematodes in Dogs. 319 



arated from the body by a narrow constriction, and throughout 

 covered by sharp spines except below where there is a deep pit. 

 Ventral disc 3 or 4 times as large as the oral one. Ova brown- 

 ish yellow, 94 to no /«. long, by 75 /* broad. 



Habitat. This is common in ducks, geese and aquatic birds, 

 has been found in the duodenum of the dog (Generali), and was 

 produced experimentally in rats, mice, moles and sparrows. 



It has been very largely availed of in tracing the pathogenesis 

 of the trematode, and hence its successive stages of growth, 

 and homes, as : i. The ovum. 2. The ciliated embryo. 3. The 

 brood capsule (redia) encysted in the lungs, etc. of a mollusc. 

 4. The daughter sporocyst in the liver. 5. The free swimming 

 young trematode moving in the water or attached to an aquatic 

 plant, ready to be taken in by its mammalian host (see Distoma 

 Hepaticum) ; are well known. 



Pathogenesis. From the nature of the armed head this trema- 

 tode can hardly fail to prove very hurtful to its host, and Generali 

 noted in his infested dog, severe duodenitis and many yellowish 

 gray spots indicating previous points of attack and phlegmasia. 



Treattnent would be by any one of the active vermifuges. 



Ascaris Marginata. Bordered A. Maw W^orm. A. 

 Mystax. Body white or pale pinkish brown, narrowed at both 

 ends, tail pointed. Male, 5 to to cm. long, tail curved and fur- 

 uished with two lateral membraneous wings and twenty-six 

 papillae on each side — two post-anal. Two spicula. Female, g 

 to 12 cm. long ; blunt tail ; vulva in anterior quarter of the body. 

 Head usually slightly curved and furnished with two broad lateral 

 alse giving the appearance of an arrowhead. Mouth triangular, 

 closed by three lips, each bearing. a tubercle iu the middle of its 

 outer surface. CEsophagus club-shaped, ending behind iu a 

 nearly globular ventricular enlargement. Ova almost globular, 

 75 /u to 80 /x in diameter, with reticulated surface. 



Habitat. Small intestine and stomach of dog, often brought 

 up in vomiting, hence the name of m.aw-worm . It is common 

 also to other species of the canine family like the fox and wolf. 

 The identity of this parasite with the Ascaris Mystax of the cat 

 is at present claimed by the majority of helminthologists in spite 

 of the marked difference in the size, and if this were accepted, 

 man must be added as a possible ho.st. 



