393 



HYMENOLEPIS ACICULA SINUATA, A NEW SPECIES 



OF TAPEWORM. 



By T. B. Rosseter, F.RM.S. 



{Read March 5th, 1909.) 



Plate 30. 



This tapeworm was taken from the intestine of Anas boschas 

 /era, commensal with other species of tapeworms. 



Including the scolex and neck it is 59*063 — 60 mm. in length. 

 Its segments throughout the strobila are broader than long. 

 The scolex is an elongated truncated cone (Plate 30, Fig. 1) 

 0*304 mm. in length, its greatest width 0*262 mm. Its apex at 

 the inversion of the rostellum has a diameter of 0*067 mm., 

 whilst the diameter of the transverse ridge is 0*185 mm. 

 There are four oval suckers approximately 0*169 mm. long. 

 The rostellum is pyriform, 0*203 mm. in length and 0*106 mm. 

 in diameter ; it bears ten sickle-shaped hooks, 0*067 — 0*068 mm. 

 in length (Figs. 1 and 14). The neck is short, rugose, and can 

 apparently be elongated. The collar at the base of the neck is 

 duplex. The primus is 05 long and 0*236 broad ; the secundus 

 0*34 long and 0*236 broad. Segmentation commences immedi- 

 ately behind the collar. The segments are aggregated or closely 

 pressed together, and are the same breadth as the neck for some 

 distance, when the ssgments become more distinct and have a 

 length of 0*034 mm. and a breadth of 0*371 mm. It may be 

 advisable to mention here that the segments throughout the 

 strobila are, until the six-hooked brood is perfected, very short 

 and very broad, and in this respect resemble those of Taenia 

 perfoliata. The early-formed genital segments are 034 mm. 

 long and 0*474 mm. broad. The mature hermaphroditic seg- 

 ments are 0*05 mm. long and 0*792 broad, whilst the changing 



