Abt. 6 



TWO NEW NEMATODES FEOM DEER DIKMANS 



of the lyre-shaped rays of the accessory bursa, (Fig. 1.) "VVliat ap- 

 pears to be the same nematode was collected by the writer from the 

 fourth stomach of cattle in Louisiana in 1927. This material, how- 

 ever, differs in some respects from that on which the original de- 

 scription was based. Sjoberg, in describing the spicules of O. Jyrata^ 

 says that the distal end consists of two parts, that is, it is bifurcated, 

 and she suggests the possibility of there being a third process. This 

 has been definitely found to be present, as may be seen from Figure 

 1. The original description further states that the dorsal ray is 

 double, the two rays touching in their posterior fifths. Examina- 

 tion of the present material shows the dorsal ray to be single, as in 

 the other members of the genus. It is 90ju, to 95/x in length and 

 bifurcates distally about 13|U, to 15|U, from the end, each bifurcation 



-f 2. 



Figure 1. — Ostertagia lyrata: 1, Bursa; 2, spicules 



again dividing near the tip. The dorsal lobe of the bursa is thick- 

 ened. Sjoberg interprets the structure supported by the lyre-shaped 

 rays as a prolongation of the genital cone. This structure is appar- 

 ently the accessory bursal membrane common to all species of the 

 genus. 



Up to the present, 23 species have been described as belonging to 

 the genus Ostertagia. Of these, 18 are reported from ruminants, 

 and 5, all from South America, from animals other than ruminants. 

 Three of the species reported from ruminants differ in some points 

 from the published generic diagnosis, and it is, therefore, desirable 

 to amend the generic diagnosis to include these species, as follows : 



OSTERTAGIA Ransom, 1907 



Generic diagnosis. — Trichostrongylidae ; Trichostrongylinae : Head, 

 less than 25|U, in diameter, with six indistinct lips or papillae sur- 



