REPTILIAN TAPEWORMS. 



certain characters as obvious in the living tapeworm which 

 could not be detected in the alcohol-preserved examples from the 

 other lizard. In the meantime I furnish a separate description 

 of the two series of tapeworms. 



The immature worms are distinctly smaller than the others, 

 which is again in favour of regarding them as different species. 

 It is interesting to note that in Varanus niloticus, a.s in Varamcs 

 varius (as will be pointed out later), a small and a comparatively 

 large species of Ichthyotcenia occur together. But it must be 

 borne in mind that in the case of Varamts niloticus they did not 

 infect the same individual. 



These worms are indeed quite small, measuring not more than 

 from 10 to 15 mm. They present quite the appearance of a fine 

 white thread, as in the case of Ichthyotcenia tidsivelli and of one 

 of the species which I describe in the present paper from Varanus 

 variits. I have studied them entire and in transverse and sagittal 

 sections ; but owing to their immaturity my description has many 

 lacunae, in consequence of which I do not propose to give a name 

 to the species. The most striking external character is one that 

 I have not met with in any other tapeworm. The base of the 

 scolex and a certain amount of the ensuing strobila was tinged of 

 a bright carmine, which I thought at first was merely a blood- 

 stain. It is not, however, blood-colour by reflected or transmitted 

 light, and is distinctly bright pink. Moreover it resisted for a 

 certain period the action of alcohol, but was ultimately washed out. 

 This pigment does not occur in the form of granules, like the 

 black, pigment which is not rare in the heads of tapeworms. It 

 is diff'used through the tissues, though I am not able to delimit 

 the regions where it occurs. It is highly characteristic and quite 

 unmistakable. Nothing of the kind appears to be mentioned by 

 Johnston in Ichthyotcenia [Acanthotcenia) tidsivelli. 



The scolex of this worm is very mobile, and the anterior end 

 (the rostellar region) can be protruded far or flattened down oi' 

 actually retracted, thus producing an apical and conical cavity 

 which might be mistaken for a sucker-like structure in an indi- 

 vidual which had been fixed in death in this position. As the 

 majority of tapeworms are always described from preserved 

 examples, it is worth while to dwell upon this great flexibility of 

 movement ; and, moreover, Riggenbach has used the presence of 

 an apical dimple as an aid to the systematic arrangement of the 

 genus Ichthyotcenia *. Among the preserved examples which I 

 also studied during life I find some with fully expanded and 

 others with retracted rostellum. This species is at least to be 

 contrasted in this respect with that described by Johnston, in 

 which the author particularly states that the rostellum is repre- 

 sented by a muscular plug which is not retractile. In the same 

 way the four suckers are very mobile and can be protruded in the 

 shape of finger-like processes. There are, of course, no hooks 



* Kev. Zool. Suisse, iv. 1896, p. 165. 



