496 PROF. C. L. BOULENGER ON FILARIID 



Yiilva 0*65-0*9 mm. from the anterior end. The long vagina 

 runs almost straight backwards. 



Ovo viviparous. Eggs thin-shelled, measuring 0*03 x 0*02 mm. 



Text-figure 4. 



Acantliocheilonema diacantha (Molin). 

 Tosterior extremity of male, lateral view. X 225. 

 c.a., caudal appendage; cl., cloaca; c.p., caudal papilla; po., post-anal papilla; 

 pr., prcanal papilla; $p., long spicule; spi., short spicule. 



ACANTHOCHEILONEMA GRACILE (Eudolphi, 1819). 



Filaria gracilis is a common parasite of Monkeys and has been 

 listed from more tliaii twenty-five species, including both Old- 

 World and New- World forms. My material is derived from the 

 peritoneal cavities of the following species, all from the Society's 

 Gardens : White-fronted Capuchin [Cehus hyjmleucus), 8moky 

 Woolly Monkey [Lagothrix inftimata), Moustache Marmoset 

 [Leontocebits mystax)^ and Squirrel Monkey (Saimiris sciiirea). 



The systematic position of this worm is somewhat uncertain. 

 Diesing, in his famous 'Revision der Nematoden ' (1860), placed 

 it in his genus Dipetalonema, a genus which is not only ill-defined, 

 but contains also widely separate forms from Birds and Reptiles. 

 In many of its characters, e. g., position in the host, structure of 

 head-papillae, (esophagus, caudal appendages, spicules, etc., Filaria 

 gracilis closely resembles certain species of Acanthochellone'ma, and 

 I have decided to include it, at least provisionally, in this genus. 



Specific diagnosis. — Acanthocheilonema : Body filiform, very 

 elongated, much diminished in breadth posteriorly. Head 

 narrow, not separated from the body by a neck-like constriction. 



Cuticle with very fine transverse striations, only visible under 

 high magnifications. 



