NEMATODE GEXUS PHYSALOPXERA. 1011 



7. Presence or absence of a cuticular sheath at the posterior 



extremity. 



8. Size of tJie eggs. 



9. Relative length of the oesophagus. 



10. Positions of the excretory pore and cervical papillae. 



The value attaching to each of these characters is indicated by 

 its position in the above list. 



Systematic Section. 



The remainder of the paper is divided into two parts. Part I. 

 contains the descriptions and diagrams of all the species 

 personally studied. Part II. gives an extract of the principal 

 characteristics of all the species not personally examined. In 

 most cases these extracts are based on the original descriptions 

 and drawings ; where this is not the case, the source is recorded 

 under the species concerned. In each part the parasites are 

 classified into three groups according to whether they were 

 di-, tetra-, or polydelphoid, the arrangement proceeding from 

 Mammals to Birds and to Reptiles. 



Ph. acidicauda, however, has been placed together with 

 Ph. prceputicdis and Ph. malayensis after the reptilian didelphoid 

 forms, because of the similarity of their female genitalia. Species 

 Inquirendse, and species which were described as belonging to 

 the genus Physaloptera but which have since been found to 

 have been misplaced, are listed at the end of Part II. 



The hosts cited after the species in Part I. are the hosts from 

 wdiich the material examined was collected ; the hosts in Part II. 

 are those from which tlie material collected formed the basis of 

 the descriptions. A moie detailed list of hosts from w]}ich the 

 separate species have been recorded is furnished by Stiles and 

 Hassall's 'Index Catalogue of Eound-worms ' (1920). 



PART I. 



Generic Diagnosis (emended). 



Superfamily Spiruroidea. 



Family PHYSALOPTERID2E. 



Subfamily PnYSALOPTERiNiE. 



Mouth with two large simple and lateral lips, each armed with 

 a variable number of teeth and carrying two external papillte. 

 CEsophagus consists of an anterior muscular and a posterior 

 glandular part. Cuticle generally reflected over the lips. Caudal 

 extremity of male with lateral alte joining each other across the 

 ventral surface in front of the anus. At least four pairs of 

 pedunculated papillae supporting the alfe; these generally ai-ranged 

 circumcloacally. A variable number of ventral caudal papillae, 



