36 ON REPTILIAN TAPEWORMS. 



While it is not apparently possible to distinguish as a separate 

 genus the two species which inhabit Amphibians, I am of opinion 

 that Lonnberg's species from Trionyx ferox will prove to be not a 

 Tetrahothriuni or an Ichthyotcenia, but another genus closely allied 

 to the latter. At present the chief anatomical difference appears 

 to be the limitation of the testes to the middle of the proglottid. 

 Finally, I think that we must retain Orejndohothriimi for those 

 Ichthyotaeniids, inhabitants of Ophidia, which possess horseshoe- 

 shaped suckers. 



§ Res'ii.me of the principal new Facts. 



It may be useful to abstract from the foregoing pages a short 

 resume of the more striking new facts which I have been able 

 to ascei'tain : — 



(1) Worms of a group belonging (in agreement with its usual 

 definition) to the genus Ichthyotcenia are more conveniently to be 

 removed and placed in the genus Acanthotcenia of von Linstow. 

 These worms are found in several species of Varaitus and are 

 limited to that genus. The same species does not occur in more 

 than one species of Varanus, but a single species of Varanus may 

 contain more than one species of Acanthotcenia parasitic in it. 



(2) In some at any rate of the species of Acanthotcenia there is 

 a la3'^er of longitudinal muscles limited to the head and neck and 

 separating the medulla from the cortical region ; these fibres are 

 arranged in bundles. This la3^er disappears and does not occur 

 in the body behind the neck. 



(3) It follows from the above statement that in the body 

 generally there is no demarcation between the medulla and 

 cortex. 



(4) The existence of numerous ventrally situated openings of 

 the uterus in a tapeworm which is assigned to a new genus 

 Ophidotceuia is a new fact so far as concerns the Cyclophyllidea 

 ( = Tetracotylea). 



(5) The diverticula of the uterus in Ophidotcenia, instead of 

 being of a character similar to the median stem, are closely 

 beset with gland-cells and probably secrete the shell of the ova, 

 there being no shell-gland in this worm. There is here a possible 

 likeness to Mesocestoides, but the details are different, 



(6) The mature eggs of Acanthotcenia varia not only tend to 

 cling together in balls, as has been described in other species 

 of the genus, but a series of distinct eggs are enclosed also, 

 in many cases, within a common sheath, which suggests a division 

 of one original egg. 



(7) A remarkable abnormality is recorded in the same 

 species, where in one proglottid the male and female ducts open 

 on to opposite sides of the body. 



