188 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 50. 



FILARIA species Morgan, 1868. 



Specific diagnosis. — Filaria (p. 179) : Long, slender white worms 

 76 to 127 mm. long. 



Host. — Castor fber. 



Location. — Peritoneal cavity. 



Locality. — United States (Micliigan?). 



In his work on the American beaver, Morgan (1868) states: 

 "Large nmiibers of a long, slender white worm, 3" to 5" in length, 

 were found in the peritoneal cavity {FilaHa.^ species not loiown)." 

 The size and site suggest that tliis worm belongs in the genus Setaria. 

 Cobbold (1879) says tliis and other worms from the beaver, noted in 

 Morgan's paper, were collected by Doctor Ely. I can not find that 

 this was the case. 



Collective genus MICROFILARIA Shipley and Fearnsides 



1906. 



Generic diagnosis. — Filariinae (p. 179) : Larval filariae circulating 

 in the blood. 



This is a collective group and hence does not have a type species. 

 I am not certain as to the author of the group name. It has been 

 credited to Magalhaes (1878), but he uses the term " micro-filarias" 

 and does not use it generically. It has also been credited to Manson 

 (1880), but he uses the form " micro-Filariae." 



ANALYTICAL KEY TO SPECIES OF MICROFILARIA. 



1. With a thick sheath or capsule. In Nj/ctoim/s species. 



MicrofUuria pTimmeri, p. ISO. 

 Without a tliick sheath or capsule 2. 



2. Well described species from Citellus hccchcyi Microfilaria rosenaui, p. 1S8. 



Undescribed or little description ; not from C. 'beecheyi 3. 



3. Long, pointed forms from Erethison Microfilaria species, p. 190. 



Form from Epimt/s rattus Filaria species, p. 190. 



MICROFILARIA ROSENAUI McCoy, 1911. 



Specific diagnosis. — Microfilaria (p. 188) : 170 to 250 //, long (aver- 

 age 220 fi) and 5.5 to 7 ju, thick. No sheath present (fig. 217). The 

 head is cylindrical, tapering to a flattened anterior extremity; the 

 portion devoid of nuclei is usually one and a half times the diameter 

 of the worm in length. The tail makes up about a fourth of the 

 length of the bod}^, and tapers gently to a rather sharp point. Cu- 

 ticle with ver}^ fine transverse striations. Inside of the body is a 

 column of nuclei more or less completely interrupted by several clear 

 spaces. The nuclei are of two varieties : Numerous spherical nuclei, 

 staining uniforudy and deeply; and less numerous nuclei, slightly 

 larger, not so regular in outline and not staining so deeply. The 



