318 LEWIS HENUY OOUGH. 



with the structure of the Cestodes, tmd because my material 

 was in a mucli better state of preservation than is usually seen. 

 Excepting tlie account of the histology and anatomy of 

 Stilesia hepatica, Wolffhiigel, the rest of this paper has 

 been prepared at Basel. 



I feel great pleasure in expressing my thanks to Prof. 

 Zschokke for his hospitality and assistance. 



My thanks are also due to Prof. Railliet, of Alfort, who 

 placed not only the original material of Stilesia vittata, 

 Eailliet, at my disposal^ but also more recent specimens of 

 both that species and of Stilesia globipnnctata (Rivolta). 

 I must also thank Prof. Colin, of the Natural History Museum 

 of Berlin, for the loan of the type-specimens of Stilesia 

 hepatica, Wolifhiigel, and Prof. Fuhrmaiiu, of Neuchatel, 

 for having kindly re-examined his specimens of Stilesia 

 sjostedti at my request and for the loan of his type- 

 specimens, thus enabling me to fix its true systematic 

 position, and for procuring material of Dibothriocephalus 

 and Tri^nophorus for me. 



To my friend Dr. 0. Huber I am indebted for the delinea- 

 tion of figs. 5, G, 7, and 12, and desire to express my thanks 

 to him here. 



I have divided this paper into two chapters. The first 

 deals with the systematic revision of the genus Stilesia; 

 the second is an account of the histology of Avitellina 

 centripunctata (Riv.). 



Revision or the Genus Stilesia, Railliet. 



The material employed in connection with this revision of 

 the genus is derived from the following sources : 



Stilesia globipunctata (Rivolta). 



(1) From the small intestine of a goat, collected in British 

 India by Leese, Irom Pi-of, Railliet's collection (No. PI 96'^). 



(2) I'rom the small intestine of a sheep, collected in 

 France, from Prof. Railliet's collection (No. P191). 



