170 MERISTIC VARIATION. [part i. 



(instead of about 20 mm.), and one with five pores measured 

 28 mm. (instead of 50 mm.). L., p. 571. 



126. Taenia. Case quoted by Leuckart from Heller of a Taenia having generative 

 openings placed on the surface of the segments. Leuckart himself has never seeu 

 an example of this variation. [Original reference not found] L., p. 570, Note. 



127. Taenia solium and T. saginata. Specimens are known 

 having two generative pores opposite each other at the same level. 

 In such cases each leads to a male and a female duct with cirrus- 

 sac and receptaculum seminis; but the organs for preparing the 

 ova are normal in construction, as the two vaginas lead to a 

 common uterus and shell-gland. Two cases only have been seen 

 by Leuckart and he cites another from Werner. L., pp. 529 

 and 571. 



128. Taenia solium in which the pores are normally alternating, 

 may be found with symmetrically developed pores ; and on the 

 contrary, T. elliptica in which they are normally symmetrical, 

 may occur with an asymmetrical arrangement. L., })p. 353 and 

 529. 



129. T. saginata: in a chain of about 6'5 metres in length, and 

 containing some 650 joints, there was found a single, heart- 

 shaped, supernumerary joint like those described ; a single joint 

 was found with two genital pores, one being on each lateral border 

 at about the same level. 



The largest number of consecutive joints having the genital 

 pores on the same side was six. Tuckerman, F., Zool. Anz., XL, 

 1888, p. 94. 



130. Taenia coenurus. Specimen observed by Leuckart in which 

 the last 8 or 10 segments shewed a transposition of the generative 

 organs, those which usually lie at the distal end being placed 

 at the proximal. This change of position was especially seen in 

 the case of organs engaged in the preparation of the ova. The 

 proximal proglottides of this individual were normal. The trans- 

 ition segment between these two regions contained two simple 

 vesiculss seminales and two marginal papillae which were on 

 opposite sides ; but in spite of the resemblance of these structures 

 to genital pores, neither opening, nor cirrus, nor vasa deferentia 

 could be distinguished. L., p. 504. 



131. Amongst chains of normal proglottides it is not rare to find 

 a segment containing male organs only. L., p. 504. 



Speaking generally, slight abnormalities are far more common 

 than great ones. Nearly every specimen of Tapeworm has in- 

 dividual peculiarities, and these generally repeat themselves in 

 the same chain of proglottides. This repetition of the same 

 abnormality in different parts of the chain is also the rule for 

 the greater abnormalities also. L., pp. 529, 572 and 573. 



