40 ASCAROIDEA 



6. Cephalobus Bastian, 1865. 



Cuticle striated. Lateral alae present, but sometimes very 

 slight. Head not distinct. Lateral organs absent or very 

 inconspicuous. Three more or less distinct lips, sometimes 

 bilobed. A single crown of three or six labial papillae present. 

 Cephalic bristles absent. Buccal capsule usually pyramidal or 

 prismoid, its wall composed of two or three rings of longitudinal 

 rods. Oesophagus with a muscular posterior bulb, and some- 

 times with a slight prebulbar swelling. Tail of male without 

 alae. Preanal and postanal papillae present. Spicules equal, 

 slightly curved, fusiform. One or two accessory pieces present. 

 Testis single. Vulva at abovit the posterior third of the body. 

 Female genital tubes paired, opposed ; the posterior branch is 

 vestigial and without ovary. The anterior ovary is often 

 reflexed. Usually oviparous. Spinneret absent. 



Hab. Usually free-living, in soil or decaying matter ; also in 

 fresh water. Sometimes parasitic or semi-parasitic. 

 Genotype : C. 2}ersegnis Bastian, 1865. 



Bastian, 1865, Trans. Linn. Soc. London, xxv, 124; 

 Micoletzky, 1922, Arch. f. Naturg., Abt. A, Ixxxvii, 267 ; Cobb, 

 1924, Jonrn. Parasitol., xi, 108. 



6a. Acrobeles v. Linstow, 1877. 



Subgenus of CepJialobus. Differs from type in the presence 

 of cephalic bristles and spines. 



Hab. Soil. 



Type : A. ciliatus v. Linstow, 1877. 



V. Linstow, 1877, Arch. f. Naturg., i, 2 ; Micoletzky, 1922, 

 Arch. f. Naturg., Aht. A, Ixxxvii, 268; Cobb, 1924, Journ. 

 Parasitol., xi, 108 ; Thorne, 1925, Trans. Amer. Microsc. Soc, 

 xliv, 171. 



Cobb (1924) maintains Acrobeles as a well-founded genus, 

 and characterizes it as follows : " Acrobeles von Linstow 

 amend. Characters of Cephalobus Bastian amend., but having 

 also a second inner circlet of labial organs, often simple and 

 conoid, sometimes relatively long and branched, in which case 

 the outer may also become compound. Pharynx narrower, 

 and uniform, with fewer separate cuticular elements. Amphids 

 though small usually visible, traversely elongate on outer 

 surface of lip region." 



He adds : " The future may very probably disclose reasons 

 for subdividing Acrobeles as thus defined and designating 

 separately a group {Acrobeloides gen. (aut. subg.) nov.) between 

 Cephalobus and Acrobeles sensu restricto — characterized by 

 having the inner and outer labial organs simple." See also 

 Thorne (1925). 



