NOTES OX THE HELMINTH PARASITES OF THE OPOS- 

 SUM (DIDELPHIS VIRGINIANA) IN SOUTHEAST 

 TEXAS. WITH DESCRIPTIONS OF FOUR NEW SPECIES 



By Asa C. Chandler 

 Rice Institute, Houston, Tex. 



Examination of a series of opossums {DidelpMs virginiana) 

 caught in the vicinity of Houston, Tex., has brought to light some 

 interesting parasitological information. There were found 3 species 

 of flukes, 2 of them new, and 4 species of nematodes, 2 of them new, 

 and 1 of these of a genus not hitherto found in North America. 



PROALARIA VARIABILIS, new species 



Figures 1, 2 



Diagnosis. — Small flukes, extremely variable in shape and size. 

 In some specimens the body is very clearly divided into anterior and 

 posterior jDortions, the anterior being considerably the larger in 

 most cases, while in others there is no obvious division at all. When 

 the flukes are flattened the anterior portion of the body may be very 

 broad and flat, but ordinaril}^ the sides of the body are rolled ven- 

 trallj^, the edges of the rolls meeting behind the holdfast organ, and 

 thus forming an overhanging margin. When lying on the side the 

 body is commonly seen to be bent sharply dorsally, the bend being 

 either anterior or posterior to the holdfast organ. The length varies 

 from 0.63 mm to 1.75 mm, while the width varies from only 325ju, 

 in a small specimen to 828/x in a large, broadly expanded specimen. 

 The measurements of a typical large specimen are about 1.T5 mm by 

 0.69 mm, while one of the smallest specimens, also with eggs in the 

 uterus, measures only 740/^ by 340;it. The majority of the specimens 

 show conspicuous glandular organs at the sides of the oral sucker, 

 but in some specimens (fig. 1, B, C, F, and H) no trace of them can 

 be found. In some individuals these structures are cup shaped and 

 suckerlike in appearance (fig. 1, A and D), in others they are pro- 

 truded in an earlike manner (fig. 1, E), and in still others thej^ ap- 

 pear as inconspicuous glands (fig. 1, G). The holdfast organ may be 

 either round or oval; it is somewhat constricted at its junction with 

 the body, thus presenting a mushroomlike appearance. In large 



No. 2939.— Proceedings U. S. National Museum, Vol. 81, Art. 16 



119343—32 1 1 



