ABT. 4 FOUR NEW TREMATODE WORMS — PRICE 11 



KEY TO THE TBBMATODE PARASITES OF THE MUSKEAT 



1. Body provided with two suckers 2. 



Body provided with one sucker 11. 



2. Acetabulum at posterior end Wardius zibethicus.' 



Acetabulum preequatorial 3. 



3. Body divided into two regions, the anterior region being flattened and 



concave and the posterior cylindrical Hemistomum craterum. 



Body not divided into two regions 4. 



4. Anterior end of body provided with a collar bearing one to two rows of 



spines 5. 



Anterior end of body not provided with collar 9. 



5. Collar bearing 22 spines arranged in a single, dorsally interrupted row. 



Echinochasmus schwartzi. 

 Collar bearing more than 22 spines arranged in a double, dorsally uninter- 

 rupted row 6. 



6. Eggs few in number ; cirrus pouch extending to middle of acetabulum. 



Echinoparyphium contiguum. 

 Eggs numerous ; cirrus pouch entirely preacetabular 7. 



7. Length 4.2 to 6.9 mm. ; '37 to 41 collar spines, 31 to 33 on rim and 2 to 5 on 



each ventral lobe Echinostomum callawayensis. 



Length more than 7 mm 8. 



8. Length 22 to 30 mm. ; 35 collar spines, 25 on rim and 5 smaller ones on each 



ventral lobe Ecliinostomum coalitum. 



Length 9.4 to 12.4 mm. ; 37 collar spines, 27 on rim and 5 on each ventral 

 lobe Echinostomum armigerum. 



9. Genital pore situated at posterior end of body Tlrotrema shillingeri. 



Genital pore preacetabular 10. 



10. Cirrus pouch slender and curved, extending caudad of acetabulum ; uterus 



passing between testes Plagiorchis proximus. 



Cirrus pouch piriform, not extending caudad of acetabulum ; uterus 

 pretesticular Psilostomum ondatrae. 



11. Ventral surface provided with longitudinal rows of glands 14. 



Ventral surface not provided with longitudinal rows of glands 12.° 



12. Genital pore postequatorial and lateral in position;, uterine coils anterior 



to cirrus pouch Nudacotyle novicia. 



Genital pore preequatorial and median in position ; uterine coils caudad 

 of cirrus pouch 13. 



13. Body oval, less than 500|ti long; cuticle smooth. 



Paramonostomum pseudalveatum. 



Body elongate, 2 to 2.5 mm. long; cuticle provided with spines on ventral 



surface of anterior half of body Paramonostomum echinum. 



14. Ventral surface provided with 3 longitudinal rows of nonprotrusible 



glands Catatropis filamentis. 



Ventral surface provided with 3 to 5 rows of protrusible glands 15. 



15. With three rows of glands Notocotyle urbanensis. 



With five rows of glands Notocotyle quinqueseriale. 



* Leidy (1888) reported what he thought to be Cladorchis suMriquetrus from the 

 muskrat, but gave no description of the parasite. Barker (1915) regards this as possibly 

 being Wardius zibethicus. 



' Leidy (1858) described a trematode as Monostomum affine from the gall bladder of a 

 nruskrat, but in view of the fact that the description is of such a nature as to make the 

 species unrecognizable, it is omitted here. 



