116 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.50. 



RANSOMUS Hall, 1916, new genus. 



Generic diagnosis. — Ransomeae (p. 115) : Anterior end of head ob- 

 liquely truncate, so that the mouth faces antero-ventrally. Buccal 

 capsule large, without teeth in its interior. Border of mouth armed 

 with a crown of numerous small, triangular, pointed processes, the 

 corona radiata (fig. 142). The median or dorsal lobe of bursa very 

 little longer than the lateral lobes. Ventro- ventral and latero-ventral 

 rays close together and parallel. Medio-lateral and posterolateral 



rays divergent. Dorsal ray and the 

 externo-dorsal rays originate sepa- 

 rately. The dorsal trunk sends out 

 two lateral branches and then divides 

 to form a bifurcate termination. 

 Spicules long, tubular, slender, and 

 alate. Gubernaculum present. Vulva 

 a short distance in front of the anus. 

 The vagina is of only moderate length. 

 The uteri are divergent, the muscular 

 Fig. 142.— ransomus rodentorum. ovijectors extending anteriorly and 

 BUCCAL CAPSULE. ENLARGED. posteriorly from their union with the 



vagina. Back of the muscular ovijector the posterior uterus turns 

 forw^ard. Eggs apparently not yet segmenting when oviposited. 



Type-species. — Ransornus rodentorum. Hall, 1916. 



This genus is named after Dr. B. H. Ransom, Chief of the Zoologi- 

 cal Division of the United States Bureau of Animal Industry, in 

 recognition of his work in parasitology. 



RANSOMUS RODENTORUM Hall, 1916, new species. 



/Synonym. — Chabertia species of Hall, 1912. 



/Specific diagnosis. — RansoTnus (p. 116) : The worms are relatively 

 short and thick. No cervical papillae observed. The esophagus is 

 club-shaped, thick, and prominent. The rectum is distinctly defined 

 but presents no features of interest. Cervical papillae not observed. 

 The cuticle is finely striate longitudinally. 



Male 1.64 to 8.19 mm. long and 290 to 300 /x thick at a point near 

 the thickest part of the esophagus, where the body attains its maxi- 

 mum diameter (fig. 143). Diameter of the head in the plane of the 

 buccal aperture is about ITO to 205 /x. Length of esophagus 685 to 

 750 /t, attaining a maximum thickness near the posterior end of 205 

 to 250 fi. The nerve ring is located at the union of the anterior and 

 middle third of the esophagus and is 400 to 465 /i from the anterior 

 end of the body. Excretory pore not observed. The bursa is rela- 

 tively short and wide (fig. 144). The tips of the externo-lateral and 



