500 



Dr. II. A. HayIisr)M 



V. Liii-stow (1884) ro;jjar(l.s Ascdris aemUnrea as a synonym 

 of A. entiicaudata, and gives an extensive list of hosts for 

 this species in consequenct'. II is fii^uies (1881) seem to 

 iiave hi'cu baseJ on mat 'rial really l)elo:iging t) P. semiteres. 



An examination of niaforiil Irom Vancllus vanelliiSj Tardus 

 merula and Slurnus vtthjaris shows that it includes two forms 

 which, while possihly hardly more than siib.si)ocios, are never- 

 theless qnito distinct and r>^co^niz:iI)le. 



P. sem'nerefi (Zeder, 1800), from VatieJIus, diflfers from the 

 rest of the material (^P. cusicaudatum) in (I) the presence of 



Fig. 3. 



0/ m m 



Forrocacum semiteres. Dorsal lip, external aspect. 

 d.r., deutigerous ridge; ?'., interlabium ; ;»., papilla. 



conspicuous lateral cervical alaj ; (2) the nuicli ln-tter deve- 

 loped condition of the intestinal csecum (see figs. 5, G) ; (3) the 

 much greater size of the lips in mature specimens (see 

 figs. 3, 4) ; and (4) the length of the spicules of the male, 

 those of P. semiteres measuring 0'77-0*8 mm., while those of 

 P. ensicaiidatum measure only O'02-0'63 mm. 



The shape of the pulp of the dorsal lip (figs. 3, 4) is very 

 similar in the two forms. Each of the two main anterior 

 lobes has an indentation in its outline, and sends out an 

 outwardly and backwardly directed " horn." In both cases 



