TWO PARA-SITIC TORMS OF THE FAMILY TETHARHYNCHIDJJ. 33 L 



excess of it in all dimensions, follows the Cestoid order of worms 

 in being flat, narrow, and thin, and measured l^jj inch in length 

 by -j-^j/g- broad and yjjij thick ; yellowish white in colour, firm but 

 flexible in structure, with closely approximated delicate transverse 

 furrows (somewhat under 100 in the space of an inch) mapping off" 

 the component segments, and deeper longitudinal wrinkles on 

 the flat anterior and posterior surfaces, giving a trilobar arrange- 

 ment to the body-constituents of the zooid (as seen in fig. 3, a 

 transverse section). It will be observed that the lower segments 

 contract somewhat instead of increasing in breadth, as in the tape- 

 worm colonies, and terminate in a sort of tubercle or nodule 

 (d, fig. 2) ; this was the case in two out of the three specimens at 

 my disposal, while the third, although somewhat contracting 

 towards the lowermost segments, yet presented a flat end — a fea- 

 ture apparently dependent upon these parasites being in the early 

 period of growth of the mature stage. 



On the broad surfaces of the head, within the upper half, are 

 seated two oval depressions, bothria, fossettes, or suckers (fig. 2, e). 

 These extend from the base of the proboscides in long diameter 

 downwards, in dimensions j^jj inch long by j^ broad by y^^- 

 deep, but subject to variations in size in individuals and according 

 to condition of tissues. A ridge slightly projecting into the 

 hollow occupies the centre of the inner wall of each sucker length- 

 wise, rendering it partially bipartite, and above branches into two, 

 one to each base of the double proboscis of its side. The head is 

 thicker at its free end as compared with that adjoining the neck ; 

 and upon this free end from before backwards, from the upper 

 end of one sucker to the other, in the centre, is an oblong plat- 

 form with a deep furrow on each lateral side mapping it off" from 

 the rounded-ofF edges of the head, while at each end of the plat- 

 form are situated the proboscides, four in all, but arranged in 

 couples, one anteriorly, one posteriorly, each couple closely conti- 

 guous to the upper end of the sucker of its side (fig. 1). To the 

 naked eye these proboscides, when exserted, look like small club- 

 shape fringed projections placed in couples in lateral apposition 

 to each other, but diverging at their free end, and give an extremely 

 rough feel to the finger when drawn against them. 



The more minute anatomy of the parasite is as follows, com- 

 mencing with the structure of the colony for facility of de- 

 scription. 



Fig. 3 is a transverse section through a segment at the middle 



