150 STRONGYLOIDEA 



agus without median or posterior swelling. Tail tapering. 

 Male with twelve to sixteen papiUiform preanal supjjlementary 

 organs and a second series of about eight such organs in the 

 cervical region. Spicules rather short and broad. Two 

 poorly-developed accessory pieces present. Testes paired, 

 opposed, outstretched. Female genital tubes paired, opposed, 

 with short, rudimentary, anterior branch and reflexed posterior 

 branch. 



Hab. Marine (in sand). 



Genotype : R. americanum Cobb, 1920. 



Cobb, 1920, Contr. Sci. Nematol, ix, 252 and key. 



Order II. STRONGYLOIDEA Weinland, 1858. 



Males with a terminal or subterminal caudal bursa, supported 

 by a system of rays consisting typically of six paired main rays 

 and a median unpaired dorsal ray with accessory branches. 

 Oesophagus more or less club-shaped, without a posterior bulb. 



Fam. 1. STRONG YLIDAE Baird, 1853. 



Buccal capsule well developed ; its anterior margin without 

 teeth or cutting-jilates, but usually bearing a leaf-crown. 



Subfam. 1. STRONG YLINAE RaiUiet, 1893. 



Buccal capsule relatively large, more or less subspherical or 

 infundibular. Dorsal gutter usually well develojDed, forming 

 a ridge in the wall of the buccal capsule and extending nearly 

 to its anterior margin. Parasites of the alimentary tract of 

 Vertebrates. 



1. Strongylus Muller, 1780. 



Syn. Sclerostoma Rudolphi, 1809, et auctt. ; Sderostomum, 

 auctt. 



Elements of external leaf-crown numerous. Internal leaf- 

 crown usually absent. Buccal capsule cup-shaped, thick- 

 walled, with an external circular ridge immediately behind its 

 anterior border. Teeth may be present towards the base of 

 the capsule. Dorsal gutter strongly developed. Bursa of 

 male small, entire. Spicules not barbed. Uterine branches 

 opposed. 



Hab. Large intestine of Equidae and Elephants. 

 Genotype : S. equinus Muller, 1780, of Looss, 1900. 



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