T. B. ROSSETER ON THE ANATOMY OF DICRANOTJENIA CORONULA. 357 



0"22 mm., presque rhomboidale, avec les ventouses anguleuses, 

 saillantes, irregulieres, large de 0"066 mm. a 0-09 mm. ; trompe 

 epaisse, large de 0*09 mm., longne de 0*06 mm., entouree d'une 

 couronne de dix-huit a vingt-qiiatre petits crochets long de 

 0*009 mm. a 0"014: mm., qui separe une partie terminale 

 hemispherique d'une partie moyenne, elargie et gonflee tout 

 autour." 



I have omitted his description of the male and female organs, 

 which I shall quote under their respective headings. 



This external description, together with his sketch of one of 

 the hooks from the rostellum, the only illustration he gives us 

 of this tape-worm, is amply sufficient to make it recognisable 

 w^hen met with either in the alimentary canal of the Duck, or 

 amongst the extruded faeces. 



Two specimens of this tape- worm, taken from the alimentary 

 canal of the Duck experimented on, were selected for investiga- 

 tion : they measured respectively 75*7 mm. and 78-9 mm. long ; 

 but then they had previously shed their uterine proglottides, 

 consequently they were much abridged. The width, that is 

 from the proximal to the distal lateral border of the terminal 

 proglottis, of the former was 1'700 mm., and the latter 2*194 mm., 

 and the length in either case 0'176 mm. At the commen- 

 cing formation of the segmented strobila the proglottides are 

 very small, being but 0'135 mm. and 0*017 mm. long. 



The length of the neck, which is unsegmented, is approximately 

 0*690 mm. ; I say approximately, because the creature has the 

 faculty of contracting or attenuating the neck, and in this 

 respect it is somewhat misleading, as in some specimens when 

 so contracted the neck is thickened and the lateral borders 

 show the segmented furrows of the future proglottides. The 

 scolex, or head, is rhomboidal ; and when the rostellum is 

 inverted has a diameter of 0-202 mm. ; but when it is everted, 

 the scolex is diminished by 0*04: mm. The suckers are four 

 stout elastic muscular bodies. At times they swell out and 

 stand up prominently above the scolex at an elevation of 

 0*017 mm. ; at other times sinking down to a flat plane surface. 

 They have, as Dujardin describes them, an irregular or angular 

 appearance, and when disassociated from the scolex they have 

 an equatorial diameter of 0*057 mm. 



The rostrum is an oval muscular bulb : it bears a crown 



