NO. 2131. 



NEMATODE PARASITE,"^ OF RODENTS— HALL. 



189 



head of the ^vc)^•m constitutes one of the clear spaces free from nuclei ; 

 one-fourth to one-sixth of the distance from the head to the tail is 

 another clear space ; two-thirds of the distance from the head to the 

 tail is another clear space containing very few nuclei ; and near the 

 tail, three-fourths to seven-eighths of the distance 

 from the head, is another. These four clear spaces 

 are practically constant; others are sometimes 

 present. The clear space two-thirds of the dis- 

 tance from the head to the tail — the third from the 

 head of the constant clear spaces — usually con- 

 tains a large number of fine granules. There are 

 usually a few fine granules near the extreme front (2. 

 of the head — the first clear space — and a small /^ 

 number are often found in the tail. Occasionally ^"-^ 

 these granules are found elsewhere. The terminal 

 nuclei in the tail are usually oval, their long axis 

 parallel to that of the worm. 



Host. — Gitelhis heechcyl. 

 Locatio7h. — Blood. 

 Locality. — California (all 



parts cast of 



the 

 and 



U 



Sierrra Nevada Mountains between Mexico 

 the Sacramento River). 



McCoy states that this parasite w^as found in 

 about 5 per cent of all host animals sxamined, but 

 the search for the adult worm w^as unsuccessful. It 

 apparently exerted no pathological influence of 

 any consequence on its host, as no deleterious efi^ects 

 were noted. 



The thickness of the parasite is said to be a little 

 less than that of the red blood corpuscles of the 

 host. 



MICROFILARIA PLIMMERI Hall, 1916, new name. 



Speci-fic diagnosis. — Microfilaria (p. 188) : Short, 

 ■with a thick capsule. 



Host. — Nyctomys si^ecies. 



Location. — Blood. 



Locality. — London (host animal from Central America). 



Under the caption " Embryo filariae found in the blood of mam- 

 mals," Plimmer (1913) notes the South American night-mouse as 

 one host. This has been placed here in the collective genus Micro- 

 filaria, and in view of the fact that this is a collective genus made up of 

 generally unassignable species, I have ventured to attach a specific 

 name to Plimmer's scanty description. I am reluctant to name 



Fig. 247. — Microfilaria 

 RosENAUi. After 

 McCoy, 1911. 



