RESEARCHES IN HELMINTHOLOGV AND PARASITOLOGY. 3 1 



[October, 1850. No. 56. See Bibliography.] 



CONTRIBUTIONS TO HELMINTHOLOGV. 



1. Ligula 7)7V<?;//5. —Body ribbon like, thin, translucent, nearly 

 smooth, faintly yellowish white, posteriorly obtusely rounded. 

 Head thickened, rounded, transversely corrugated, yellowish. 

 Extremity triangularly rounded, laterally compressed, front and 

 back, with a short, longitudinal, contracted depression. 



Whole length i inch 9 lines ; breadth of body i-3d line ; thick- 

 ness i-i2th line ; length of head i line ; breadth i-4th line ; thick- 

 ness I -9th line. 



Habitation and Remarks. — This species was sent to me by my 

 friend, Prof. S. F. Baird, of Carlisle, with the note "Found em- 

 bedded in the muscles of the back of Triton ( Cynops) dorsa/is. ' ' It 

 is the smallest species which has as yet been discovered, and the 

 first among batrachian reptilia. The specimen sent to me consisted 

 of two fragments of the same individual preserved in alcohol. Ex- 

 amined beneath the microscope it presented no trace of articulation 

 or interior definite organs. 



2. Pcntastomum Didclphidis \'irginian£B. — Body subcylindrical, 

 curved one-third or one-half a circle, dorsum convex, ventrum con- 

 cave, posteriorly narrowed and constricted a short distance from the 

 extremity, which is rounded. Color white, opaque. Composed 

 of forty or fewer annulations. Head posteriorly convex, anteriorly 

 plain or slightly concave ; mouth nearly round ; hooks simple, situ- 

 ated in a curved line of which the mouth forms the center. 



Whole length 3 to 5 lines ; breadth 3-5ths of a line ; annuli gener- 

 ally I -80th inch wide ; mouth i -200th inch in diameter ; hooks 

 i-2ooth inch long. 



Habitation and Remarks. — I found 9 individuals of this entozoon 

 in C-shaped cysts, the circle being 2 lines in diameter, imbedded in 

 the liver just beneath the peritoneal surface in Didelphis virginiana. 

 It may probably be the Pentastomum szibcyli^idricum of Diesing,* 

 which was found in cysts upon the liver of two South American 

 species of Didelphis and several other animals ; but the largest of 

 those found in our D. virginiana is equal to the smallest of P. 

 subcylindricum, and has not more than one-half the number of annu- 

 lations. 



3. Peyitastomum eiiryzonum, Diesing. 



*Annal. d. Wien. Mus. i, p. 21. Dujardin : Hist. Nat. des Helminthes, p. 

 305. Diesing : Systema Helminthun, vol. I, p. 611. 



