58 CEYLON PEARL OYSTER REPORT. 



and with practically no pedicels. Neck long. Division between proglottides feebly 

 marked, no constriction or overlapping, and the dividing line does not reach the edges. 

 Sides smooth and almost parallel. Reproductive pores irregularly alternate. 

 Habitat : Intestine of Myliobatis maculata. 



Diagonobothrium, n. gen. 



Head 2 '3 millims. in length, about 1 millim. in breadth. There is a large terminal 

 muscular sucker and two ear-like bothridia which run down right and left of the 

 head. One edge of each of these bothridia runs forward obliquely, and loses itself 

 in the crinkled membrane which surrounds the terminal sucker. There is only one 

 edge on each side thus prolonged, and the two prolongations cross one another at 

 about a right angle. The head is thus asymmetrical. The neck is long and shows 

 hardly any structure. 



Diagonobothrium asymmetrum, n. sp. Plate III., fig. 47. 



A single specimen of a curious tapeworm was found, with Anthobothrium crispum, 

 in the intestine of Myliobatis maculata taken in Dutch Bay. Unfortunately the 

 head and neck, which showed no strobilization and no structure, were alone taken. 

 The head consists of a very large and muscular sucker, centrally placed and terminal. 

 The sucker is surrounded by a rather wrinkled membrane. The head is 2 "3 millims. 

 long and anteriorly 1 '2 millims. wider ; its average width is about 1 millim. 



Each side of the head are two somewhat ear-shaped lateral, hollow bothridia, and 

 the peculiar feature of the head is that one edge of the bothridia is continued up on 

 to the membrane which surrounds the terminal sucker in an oblique manner 

 (Plate III., fig. 47). The other edge of each bothridia is not so prolonged. Thus it 

 comes about that these prolonged edges cross one another, one being on one side, and 

 the other being on the other side of the head. Hence the head is not symmetrical 

 about any plane, and it would be impossible to cut it into two symmetrical " looking- 

 glass " halves. This feature is very unusual in a Cestode, and one could not put 

 from one's mind that it might be an abnormality, especially as only one specimen was 

 taken, and that without any proglottides. 



The neck was long and showed little structure, and it was broken across before it 

 began to segment. 



Habitat : The intestine of Myliobatis maculata. 



Rhoptrobothrium, n. gen. 



Minute forms. Head with four bothridia surrounding a myzorhynchus which 

 carries four suckers. Bothridia stalked and leaf-like, with the terminal end cut off and 

 forming an areola. Head extends behind the insertions of the stalk of the bothridia 

 and is followed by a neck, 



