PAI!. \SITIC -vVnKMS I.KIl'KK AND ATKINSON. l!i 



The genital atrium i> \er\ lar^c and has a lleshv wall. The pores are .single and 

 "ii the .siiiie side throughout the slrobila. The massive atrium occupies nearlv the 

 whole border of the segment. The outer measurement of t he atrium is 0'2:! mm., while 

 its cavity is O'l.'imm. across. The cirrus (.v/*) is usuallv extruded and hooked back- 

 wards in Dearly every segment. It measures '05 mm., and its surface is roughened 

 by ridges. The broad vagina crosses the segment, and. after turning once upon itself, 

 runs towards the centre. Two excretorv canals run down either side, immediately 

 inieni.-illy to the genital atrium, throughout the segments. The outer canal is small, 

 t he inner nearlv twice as wide. 



:!0. Tetrabothrius priestleyi, Leip. and Atk. (PI. IV, fig. 28.) 



Tetrabothrius priestleyi, Leiper and Atkinson, P/v.-. %<ml. ,sV>r., 1914, p. I'i'.'i. 



Sti-nliila 10 i-iu. IIIIILT, excessi\-ely slender, with large tulip-like head. Testes 17-liO. Near to 

 '/'. /'I I: I'll 111, l''uhriiiaim. 



//"*/. -A Frigate bird (Finjntn uiji/iln or F. nrirl], shot at South Trinidad 

 ( Slat. :;('>) ; intestine. 



External Appearance. The worms measure from 10 to LL cm. in length, and for 

 the greater part are exceedingly slender. The segments become enlarged only towards 

 the caudal end. They are pearly white in the anterior thin part, changing to yellowish- 

 \\hiie posteriorly. The worms were removed from the intestine in a tangled mass, and 

 owing to their long slender necks were difficult to separate from one another. 



Hi-mi. The head is comparatively large, and is armed with four suckers placed on 

 the sides and not showing on the top of the head. The suckers are narrow in front 

 and expand to their greatest width behind. The head is 0'55 mm. long, and attains 

 (C44 mm. in breadth at its broadest part. Each sucker is 0'42 mm. long and 0'22 mm. 

 wide at its broadest part. The head-region is well-defined. There is a slight con- 

 striction behind the suckers, and this is succeeded by a fairly long neck, before the 

 segments make their appearance. 



--The segments figured (PI. IV, fig. 28) are from about the middle of 

 t lie worm. .Maturity is late. The segments stain diffusely with haematoxyliu. They 

 arc broader than long, measuring O'O mm. bv 0'.". mm. Their shape does not varv 



I L J 



much, but the\ be,-,, me thicker and broader toward the posterior end. The genital 

 atria are unilateral, large and rounded, measuring (VI 4 mm. They open laterally. 

 The cirrus is rounded and unarmed, measuring irl mm. in length and ()()(; mm. in 

 its greatest breadth. A short vagina lies behind it. The testes are relatively large 

 and lorm about seventeen to twenty uronps. They are confined to the central part 

 of the segment. In some of them the bulk is increased markedly, and stained 

 nuclei are found only round the periphery. The yolk-gland is placed in front of 

 them, in the middle of the cephalic bolder. It is large, circular, and stains deeply, 

 measuring (CD | mm. across. A single excretory canal runs down either side, externally 

 to the testes. The canal is broad and runs internally to the genital atrium. A most 



