338 suKftEON r. h. welch on the akatomt or 



a gradually thinning cylinder of tissue from the head enveloped 

 the first part of the colony to this extent (fig. 17, b). There was 

 no trace of genital orifices in any of the segments. 



A vertical section through the head is seen in fig. 16, and a 

 transverse section in fig. 19, showing the arrangement for the 

 movements of the proboscis to be similar in both parasitic forms. 

 From the bottom of the bulbs a dense mass of fibres pass, which 

 form a circular baud traceable through the centre of the head 

 downwards (fig. 16, e) ; these are evidently for the retention of 

 the bulbs in their normal vertical position in the head. The pro- 

 boscides in this species are narrow and elongated, .^i^ inch long 

 bv — ^ — inch in diameter ; the booklets are of one shape and not 



•' 3000 . '■ 



80 thickly studded, arranged m parallel spiral lines, along each of 

 which on the side of the proboscis in view under the microscope 

 five can be counted ; and this would give to each proboscis about 

 400 booklets in all (fig. 18); the average size of the booklets is 

 ^ inch. The proboscides emerge from the free end of the head 



10 ^ 



in separate circular apertures placed at equal distances from each 

 other ; and these are mere orifices with no appendages. Immediately 

 beneath the skin of the head is an immense quantity of dark, black 

 pigment in the form of minute oval masses often arranged linearly, 

 and also oval masses about g^pQ inch in diameter of a beautiful 

 purple colour ; and these give the special tinge to this part of 

 the parasite. Surrounding the bulbs is a delicate fibrous layer ; 

 and in the parenchyma external to it are a few inorganic calca- 

 reous nodules arranged at definite intervals, and radiating and 

 circular and longitudinal muscular fibres regularly penetrating it. 



In fig. 17, a vertical section, is seen the mode of junction of the 

 colony with the head. A distinct transverse band of fibrous tissue 

 {d) forms the boundary line ; and from this strong radiating bands 

 (c) diverge upwards into the head, forming the link of'the one to 

 other. The structure of the enveloping cylinder of the commence- 

 ment of the colony is similar to the parietes of the head ; the 

 cuticle at the free thin end is reflected upwards and inwards as a 

 delicate layer to the level of the junction of colony and head, and 

 is there continuous with the skin of the former. The first seg- 

 ments of the colony are very delicate in aspect and of great 

 tenuity ; and the collar prolongation from the head would act as a 

 protection against external harmful influences. 



The colony is distinctly segmented at intervals of about y^^ 

 inch for the first Ig inch, and, to the naked eye, more approac})eg 



