ART. 20. HOOKWORMS OF THE GENUS UNCINARIA RANSOM. 3 



Parasitic in intestine of Meles taxus in Europe. Not certainly 

 known as yet to occur in other animals. 



UNCINARIA STENOCEPHALA (Railliet, 1884). 



Synonym. — Uncinana polaris Looss, 1911. 



SpecifiG diagnosis.— {]ncm2iV\&: Male about 7 (5.6 to 8.5) mm., 

 female about 10 (7.7 to 12) mm. long. The ventral wall of the 

 mouth capsule when viewed in optical section from the side is con- 

 siderably curved as a rule (figs. 1, 5). The boundary line between 

 the thicker ventral portion and the thinner dorsal portion of the 

 mouth capsule wall (side view) anteriorly continues to curve toward 

 the dorsum and meets the anterior border of the mouth capsule 

 obliquely after crossing the cord of tissue which terminates in the 

 lateral cephalic papilla (figs. 1, 5, x). Esophagus of male about 

 0.75 mm., of female about 0.85 mm. long. Lateral lobes of male 

 bursa rather long, considerably more semi-oval than semicircular in 

 shape. Medio-lateral ray of about the same width as the externo- 

 lateral ray and the postero-lateral ray (figs. % 6). Dorsal ray bifur- 

 cated distally, each branch tridigitate (figs. 3, 7). Spicules 0.64 to 

 0.76 mm. long with sharply pointed tips. Tail of female 150 to 2-90 a 

 long; tip of tail, into which the caudal bristle is inserted, bluntly 

 rounded (figs. 4, 8). Vulva 5 to 7.5 mm. from anterior end of body. 



Parasitic in the intestine of the dog in Europe (type host and type 

 locality). Common in fur foxes in Northern North America. Has 

 also been found in the dog in Alaska (Hadwen) and in the hog (in 

 stomach) at Ottawa, Canada (Hadwen). 



REMARKS. 



A lateral view of the head is usually more readily secured in 

 mounted specimens of U. crinifonnis and U. sfenocephala and in my 

 experience is more useful for diagnostic purposes than a dorsal view. 

 Dorsal views give very variable pictures because of differences in the 

 tilting of the head in different specimens, and comparisons of speci- 

 mens and of drawings are more difficult than in the case of lateral 

 views. It may be noted as of interest that Railliet's drawing of the 

 dorsal view of the head of Un^inaria sfenocephala (see Railliet, 

 1893a fig. 331) corresponds vei-y well with the appearance frequently 

 shown by specimens of U. polaris (U. S. N. M., 3250) which happen 

 to be less tilted than in the view pictured by Looss (1911, fig. 108). 



Looss (1911, p. 213) states that the boundary line between the 

 thicker ventral portion and the thinner dorsal portion of the mouth- 

 capsule wall of U. polaris is nearly straight and he shows it but very 

 slightly curved in his drawing (Looss, 1911, fig. 107). In full lateral 

 views of the mouth-capsule of U. polaris {= U. stetwceph^la) from 

 the fox (fig. 1, a?), and of U. stenocephala from the dog (fig. 5, x) I 

 have found it more curved than Looss has described and figured it 



