No. 1. — CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY 

 OF THE MUSEUxM OF COMPARATIVE ZOOLOGY AT HARVARD 

 COLLEGE, UNDER THE DIRECTION OF E. L. MARK, No. 148. 



The Anatomy of Hemiurus crenatus (Rud.) Liihe, an Appen- 

 diculate Trematode. 



By Clakence H. Lander, 



CONTENTS. 



PAGE 



Introduction 1 



External cliaracters 2 



Body wall 3 



Parenchyma 5 



PAGE 



Excretory system 13 



Male sexual organs 16 



Female sexual organs 20 



Bibliography 25 



Digestive system 11 Explanation of plates 28 



Introduction. 



This species of appendiculate distome was first described by Rudolphi 

 ('02, pp. 76-78) as Fasciola crenata, and later ('09, pp. 404, 405, tab. 5, 

 fig 1.) as Distoma creuatum. It has since been included under Dis- 

 tomum(or Apoblema) appendiculatum by Rudolphi ('19), Monticelli ('91), 

 Milhliug ('98), and also under Distomum ventricosum by Wagener ('60). 

 It is described as Distomum ocreatum by Olsson ('67), and Linton 

 (:00), as Apoblema ocreatum by Juel ('89), and as Hemiurus ocreatus 

 by Looss ('99). The name Hemiurus crenatus was first applied to it 

 by Ltihe ( : 01), who gives its synonomy and a brief characterization 

 of the species. The genus Hemiurus was established by Looss ('99), 

 who includes under it all appendiculate distomes except those lacking an 

 appendix or having an extremely small one. Llihe proposes to raise 

 the genus to the rank of a family, under which he would include twelve 

 genera. He describes three species belonging to Hemiurus s.str. and 

 mentions two others which are perhaps also to be included in the genus. 

 It is very doubtful if the specimen shown in Olsson's Figure 98 is 

 Hemiurus crenatus, since the ventral sucker is represented as twice 

 as large as the oral sucker, while in all the specimens I have examined 

 the suckers are very nearly equal in size. In Linton's Figure 19 

 (Plate 35) the pars prostatica is represented as being four or five times 

 as long as it is in any specimens I have studied, and I think it probable 



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