C'ESTODK AND NEMATODE PAKASITES. 67 



Tiarabotkriuin, n. gen. 



Aliimt II millims. fco 12 millims. long. Head with four sessile bothridia, each 

 divided into twelve transverse areolas; the bothridia can be raised off the head 

 anteriorly. Two stout muscles enter the head laterally and split up into four muscles 

 on each side, two of which are inserted into each bothridium. Definite neck present, 

 provided with an extensile collar. Proglottides with slightly concave sides, divided 

 from each other by perfectly flat partitions. Genital pores alternate. Penis with 

 numerous spines. 



Tiarabotlirium javanicum, n. sp. Plate IV., figs. 65, 66, 67 and 68. 



Length of the worm 11 millims. to 12 millims. Breadth of head 1 millim., 

 average breadth of body 0'5 millim. 



The head bears four bothridia, each divided by transverse ridges into twelve 

 areolas, which, since each bothridium is oval in shape and rather pointed at each end, 

 are very diverse in size, the anterior and posterior areolas being much smaller than 

 the median. The bothridia are sessile upon the head, and judging from the preserved 

 specimens were closely attached to the head by their whole inner surface. However, 

 the drawing made by one of us of a living specimen shows that they are capable of 

 standing out from the head anteriorly for about one-quarter to one-third of their 

 length. The remainder of the bothridium remains, however, always in continuity 

 with the head, and there is never any question of a stalk. The presence of the 

 bothridia with the areolas gives the head something the appearance of a spherical 

 Chinese lantern (Plate IV., figs. 66 and 67). 



Longitudinal sections show that the head is a rather more flattened globe than is 

 our earth. The interior of this globe consists of dense connective tissue, but between 

 this and the inner faces of the bothridia is a layer of very loose tissue, and it is by the 

 play this loose tissue allows that the bothridia can be in the anterior half raised a 

 little away from the surface of the head (Plate IV, figs. 67 and 68). 



Two very stout lateral muscles enter the head from the neck. They soon split up 

 into eight separate muscles, of which two are dorsal, two are ventral, and two are 

 riffht and two are left laterals. There is a lateral and a dorsal behind each of the 

 dorsal bothria, and a lateral and a ventral behind each ventral hothria, As these 

 muscles pass forward the laterals die out, hut the two dorsals and the two ventrals 

 aie continued forward and break up into a number of small strands, which ultimately 

 disappear in the connective-tissue mass which occupies the centre of the head. The 

 water vascular system lies laterally, but there are at one or two levels cross communi- 

 cations between the right and left vessels, and the vessels on each side are very 

 convoluted and coiled; as they pass down the neck they take up the position of 

 dorsal and ventral vessels on each side of each segment. 



The head is followed by a definite neck, and this is clothed by a very turn-down 



K 2 



