82 CEYLON PEART, OYSTER REPORT. 



the mature ones at the posterior end are perhaps twice as long as broad. Here the 

 remains of the penis are visible, and it seems to bear spicules. In the few proglottides 

 where it is visible, the reproductive pores appear to be regularly alternate. In 

 appearance this somewhat resembles van Beneden's figure of one phase of E. 

 minimum* It is however, we believe, a distinct species. 



The diagnosis of Echeneibothrium walga is as follows : 



Head provided with four long stalks, each bearing a pair of opposed half bothridia, 

 each composed of twenty- four areolas. Body minute, neck hardly pi-esent, repro- 

 ductive pores regularly alternate. 



Habitat : Intestine of Trygon walga. 



Echeneibothrium ceylonicum, n. sp. Plate VI., figs. 102 and 103. 



Four specimens varying in length from 8 millims. to 25 millims. were taken from 

 the intestine of Trygon walga. The head is comparatively small and resembles in 

 general architecture the head of Echeneibothrium trygonis, but it differs considerably 

 in details. The head itself is longer and takes up a greater proportion of the whole 

 body. It splits into four short arms, and each of these bears a bothridium. The 

 bothridia are built up of fourteen areolas, of which one is terminal at each end and 

 twelve are paired, as in the figure (Plate VI., fig. 103). Special muscles run from 

 each arm down the neck, and the several arms are very mobile and contractile and 

 take on different shapes in different states of contraction. 



The body is stouter than in the case of Echeneibothrium trygonis ; the neck is of 

 fair length ; the proglottides bulge out a good deal at the sides, so that the outline 

 is like a thread of beads. The reproductive pore is median. The mature proglottides 

 are never more than twice as long as they are broad, and their sides are curved, not 

 straight and parallel. Mixed with the adults were a number of young forms, with 

 tapering bodies, but not yet divided into proglottides. 



The diagnosis of Echeneibothrium. ceylonicum may run : 



Length up to 25 millims. Head with four inwardly directed bothridia, bearing 

 fourteen areolas ; of these, two are terminal and twelve are paired. Proglottides 

 rounded at the side, the oldest, ready to break off, never more than twice the length 

 of the breadth. Reproductive pore median. 



Habitat : Intestine of Trygon walga. 



Phyllobothrhvm lactuca, van Beneden. Plate VI., figs. 104 (a and b) and 105. 



This is by far the longest Cestode found in Trygon walga. It attained in one 

 preserved specimen the length of 33 centime. In this particular specimen the width 

 hardly exceeded 2 millims., and the texture was flimsy and soft, but in another specimen, 

 which was in pieces, the consistency of the worm is stiff and almost brittle, and the 

 width had swollen out to 4"5 millims. and, although broken up, its length could have 



* 'Mem, Ac. Belgique,' xxv., 1850, Plate ii., fig. 3. 



