176 



rR0CEEDING8 OF THE NATIONAL MUSEUM. 



VOL. 50. 



Male unknown. 



Female 8 to 11.5 mm. long and 1 mm. thick. Body attenuate ante- 

 riorly and very much thicker posteriorly (fig. 230). The posterior 

 extremity of the body terminates in a long, rounded, mucronate tip 



230. 

 Figs. 230-233.— RicTtn-ARioioEs ampiuacanthum. 230, Fem.vle. a, Natueal size; 6, enlakged; c, 



PORTION OF BODY. AFTER DiESING, 1857. 231, POSTERIOR EXTREMITY OF FEMALE. ENI.ARGED. AFTER 



DiEsiNG, 1857. 232, Posterior extremity of female, showing 3 rows of spines. Enlarged 

 After Diesing, 1857. 233, Profile view of cuticular spines. Enlarged. After Diesing, 1857. 



(fig. 231). The cuticle bears three longitudinal series (fig. 232) of 

 strong, posteriorly directed hooks (fig. 233). 



Host. — Oxymycterus rufus {Lemmus dasytrichus) . 



Location. — Small intestine. 



Locality, — Ytarere, Brazil. 



Jiigerskiold (1909) has noted that if Diesing's descriptions and fig- 

 ures are correct, this species can not remain in the genus Rictularia. 

 In view of the fact that Diesing (1857) has revised his description 

 to cover the presence of three rows of hooks instead of two, and in 

 view of the fact that von Drasche (1882) has examined the speci- 

 mens and found no changes in the description necessary, it seems de- 



