I. A REVISION OF THE INDIAN SPECIES 

 OF THE GENUS PHYLLOBOTHRIUM. 



By T. SouTHWELi., A.R.C.S., F.Z.S, Director of Fisheries, 

 Bengal, and B. Prashad, D.Sc. 



(With Plate I.) 



During recent years large numbers of Cestoda have been collect- 

 ed in India and Ceylon. Except in a few instances the descriptions 

 of such of these parasites as have been described have been based 

 almost exclusively on external characters, and such characters are 

 often insufficient to identify the parasite. The variability of form 

 assumed by all cestodes during the process of preservation, and 

 the differences due to age and between the mature and immature 

 worms, makes identification by means of external characters alone 

 very difficult. Further, descriptions of parasites which do not in- 

 clude an account of the anatomy cannot be regarded as satis- 

 factory. 



The genus Phyllohothrium was first defined by Van Beneden 

 in the year 1849. Unfortunately, we have been unable to obtain 

 a copy of the original memoir. In 1850 he published a description 

 of the two species P. thridax and P. lactuca, while in 1858 he des- 

 cribed the species P. auricula. A description of two more species, 

 P. hrassica and P. fallax, followed in 1871. 



In 1850 the same author (i) defines the characters of the genus 

 Phyllohothrium as follows : — 



' ' The four bothridia are sessile ; their concavities face exter- 

 nally. They are very mobile and have their edges frilled and puck- 

 ered like the leaves of a lettuce." 



In 1888 Zschokke (14) published a very careful account of the 

 anatomy of P. thridax and P. dohrni {Orygmatohothrium dohrni). 

 An excellent description of P. vagans, Haswell, was given by Has- 

 well (8) ; and quite recently Yoshida (13) has given a further ac- 

 count of the anatomy of P. lactuca, Van Ben. Linton (5) described 

 two species P. foliatum and P. thysanocephalum, and also added 

 some notes on Leidy's species P. loliginis, but he eventually found 

 it necessary to estabhsh the genus Thysanocephalum for his P. ihy- 

 sanoceaphalum and changed the name of this species to Thysanoce- 

 phalum crispum, though according to the accepted rules of zoological 

 nomenclature it should be known as T. thysanocephalum. 



Shipley and Hornell (11) described three new species, viz.— 

 P. hlakei, P. minutum and P. pammicrum, from external char- 

 acters alone, giving no accoujit of their anatomy. Shipley had also 



