76 DR. F. E. BEDDARD ON THE 



Monitoi' niloticus. The latest statement known to me is that of 

 Cholodkovsky *, who has defined Duthiersia by {inter alia) the 

 fact that the " Bothridia have the appearance of a funnel with 

 blind narrow ends formed behind." This definition presumably' 

 implies the existence of only one species of the genus. 



The above brief resume shows that, while Perrier examined 

 examples of Duthiersia fi'om both the Nilotic and the Indian 

 species of Monitors and asserted the existence of the posterior 

 orifice of the funnel formed by the partial coalescence of the two 

 lips of the bothrium in both of these, subsequent observers based 

 their results upon the personal examination of one only of the two 

 alleged species ; and also shows that there is a consensus of opinion 

 that no posterior orifice exists in examples from Monitor niloticus, 

 while it is asserted to exist in examples from Indian Monitors. 

 These observers finally appear, on the whole, to have concluded that 

 their own observations, though made upon one set of individuals 

 only (whether from Africa or India), applied to the others ex- 

 amined by their fellow- workers, and that the genus Duthiersia 

 was definitely to be characterised by the possession or non- 

 possession of these orifices according to each observer's own 

 discovery of fact. I have made myself an examination, as already 

 stated, of examples of Duthiersia from both African and Indian 

 species of Monitor, and I cannot see why the obvious differences 

 pointed out by Perrier liave not been universally accepted. To 

 these I have some fresh observations to add which, as I think,, 

 entirely justify the position taken by Perrier. 



Perrier's figures show the great difference in the general form 

 of the scolex in the two species, which is, moreover, much larger 

 in D. expansa than in D. fimhriata (as we must, of course, call 

 Perrier's D. elegans). I have already described the apical pit in 

 D. fimhriata, which is not to be found in D. expansa, and I agree 

 with other observers that the posterior aperture of the bothria 

 does not exist in D. fimhriata. I have examined several series of 

 sections both transverse and longitudinal, and can find no trace 

 of this orifice. In D. expansa, on the other hand, it is exceedingly 

 obvious though very minute. It lies closely adpressed to the 

 commencing strobila to which the posterior end of the folds 

 forming the bothrium are attached, instead of, as in D. fimhriata, 

 turning upwards to be attached at a point much higher up and 

 within the shelter of the lateral folds forming the bothrium. At 

 the point of opening of the orifice the fused bothrial folds project 

 laterally as a papilla upon the side of the strobila ; but the actual 

 orifice is not upon the apex of this papilla, but upon its inner 

 side. There are other differences between the scolices of these 

 two species of Duthiersia. In D. expansa, in tracing a series of 

 sections from the strobila region forwards, the axis of the scolex 

 is more sharply defined than in the other species. This is seen 

 in transverse sections to be due to the fact that the flaps of 



* Trav. Soc. Imp. Nat. Petrograd, xlv. 1914, p. 62. 



