TREM ATODES OF AUSTRALIAN BIRDS. 2 1 I 



last in the dorsal bay is the smallest, 0*0427 x 00213 mm. 

 and they gradually increase in size to the fifteenth, in the 

 vicinity of which a number are equal in size and measure 

 0*122 x 0*048 mm. On each ventral angle there is a group 

 of three spines not lying in series with the row round the 

 edge and pointing obliquely inwards towards the middle 

 line. The innermost, which is the largest, measures 0*1602 

 x 0*0534 mm., the second 0*1335 X 0*0427, and the third 

 which is much smaller than the others 0*096 x 0*026 mm. 

 All the collar spines have a flattened rod-like form, bluntly 

 pointed at each end. 



The integument of the body is entirely devoid of spines. 

 The oral sucker is broader than long, 0*194 X 0*116 in the 

 smallest, and 0*29 x 0*232 in the largest specimen. The 

 ventral sucker measures 0*97 x 0*77 mm. in the smallest, 

 and 1*55 x 1*21 mm. in the largest specimen, so that the 

 ratio of the oral to the ventral is about 1 : 5. The pharynx 

 is elongated oval, nearly twice as long as broad, 0*175 

 x 0*097 mm. in the smallest, and 0*31 x 0*19 mm. in the 

 largest individual. The bifurcation of the intestine lies 

 some distance behind the anterior edge of the ventral 

 sucker. 



The intestinal limbs immediately run straight out to the 

 sides of the body, and course parallel to the sides of the 

 body up to their termination near the posterior extremity. 



The main stem of the excretory vesicle is very long and 

 wide, and divides into two large arms just behind the 

 posterior testis. The arms run forwards to the middle of 

 the ventral sucker, giving off in their course, on the outer 

 side, many branches. 



The two large cerebral ganglia lie one on either side of 

 the pharynx, immediately behind the oral sucker, and are 

 joined together by a transverse commissure that passes on 

 the dorsal side of the pharynx. The genital pore is situated 



