SEA-FISHERIES LABORATORY. 309 



Echeneibothrium Yariabile, van Beneden. — Figs. 19, A, B. 



Hosts : Raia clavata, Carnarvon Bay, Duddon Banks, 

 Bahama Bank, and off-shore grounds ; R. batis, off-shore 

 grounds ; Galeus vulgaris, New Quay. This is, perhaps, 

 the commonest and most widely distributed cestode 

 obtained during the past year. 



The genus Echeneibothrium was founded by van 

 Beneden to receive cestodes with the following charac- 

 ters : — The four bothria of the scolex carried each on a 

 long and protractile pedicel ; bothria extraordinarily 

 variable in form; each distinguished by regular trans- 

 verse folds along the entire length of the bothrium. 



These folds resemble the transverse lamellae of the 

 adhesive sucking organ of the fish Echeneis, a resemblance 

 which suggested the generic name. 



The most striking character of this species is its 

 astonishing variability. Figs. 19 A, B represent the two 

 most common varieties which I have observed. All these 

 cestodes were preserved in the same way: that is, they 

 were killed by immersion in fresh water for about a 

 quarter of an hour, and then put into 4 per cent, formalin. 

 The difference in the characters of both bothria and 

 myzorhynchus is such as almost to lead one to suspect 

 that the worms belonged to different species. 



Variety A (Fig. 19 A) best answers to the 

 characters given by van Beneden in his original diagnosis 

 of the species. In these worms the myzorhynchus is 

 long and slender and is provided with a small accessory 

 sucker at its tip. In the figure it is almost concealed, 

 owing to the necessity of so arranging the scolex as to 

 get a good view of the most characteristic bothria. Each 

 of the latter structures is thin and leaf-like, but the 

 posterior extremities are rolled up and present a 

 characteristic notching of the edges and backs. The 



