8 PROCEEDIlSrGS OF THE NATIONAL MUSEUM vol. 78 



body, measure 22.8^ by 11.4/a, but which are absent or very small on 

 the head and tail." F. arator, on the other hand, has a cuticle rough- 

 ened by what seems to be a hardened excretion ; there is no regularity 

 in the size of the elevations, and they are irregularly distributed in 

 patches. Whether or not this roughness of the cuticle is comparable 

 with that described by van Thiel, I am unable to determine. His 

 figure of the jjrotuberances does not in any way resemble the rough- 

 ened cuticle of F. arator. 



In spite of these differences, the two species show a number of 

 striking resemblances. Both are parasites of the lungs of monkeys 

 and are alike in general form, structure of the mouth and esophagus, 

 position of the vulva, and the almost terminal position of the anus 

 in both sexes, and in the form of the embryos. It is quite possible 

 that other related forms w^ill be found in the lungs of South Ameri- 

 can primates. 



The genus Filariopsis was erected by van Thiel (1926) for a worm 

 which was collected from the lungs of Surinam howler monkeys 

 {Aloua,ta=Mycetes senicuJus Linnaeus), and referred by him to the 

 Filariidae. The genus differs radically from typical filariae in the 

 posterior position of the vulva, in the short muscular esophagus, and 

 in the noncoiled tail of the male. It is possible, as suggested by 

 Dr. M. C. Hall in correspondence, that the genus Filariopsis belongs 

 with the spirurids rather than the filariids. Its posterior vulva sug- 

 gests this, but its other peculiar characters — short muscular esoph- 

 agus, three inconspicuous lips, and noncoiled, nonalate tail of the 

 male — are no more characteristic of the spirurids than of the filariids. 

 The lack of paired lips, the very slender bod}^, the position in the 

 host, and the uteri filled with microfilaria-like embryos are strongly 

 suggestive of relationship with the filariae. The worm can not go 

 into any of the families of Spirurata, either in the Spiruroidea or 

 Filariodidea, as at present constituted, and a new family, Filariops- 

 idae, is therefore proposed for it ; this family is tentatively placed in 

 the superfamily Filarloldea. The following definition is tentatively 

 suggested for the family: 



FILARIOPSIDAE, new family 



Faviily diagnosis. — Filarioidea: Body very long and slender, cy- 

 lindrical for nearly its entire length. Mouth surrounded by three 

 lips, wdiich may be very inconspicuous; no chitinized buccal cavit}'. 

 Esophagus short, thick, and muscular. Cuticle without distinct 

 striations, but with conical elevations or a roughness produced by 

 a hardened secretion. Tail of male very short, not coiled, and vvith 

 very small alae or none at all, with or without papillae. Spicules 

 equal, sometimes united; gubernaculum present, either single or 



