440 DR. F. E. BEDDARD OX 



genera is by Ransom *, who distinguishes the three by the 

 following salient characters — which I withdraw from his fuller 

 diagnosis : — 



Idiogenes. — Small worms with weak musculature. Genital pores 

 unilateral (except in /. otldis). Suckers unarmed. Cirrus- 

 sac large. Eggs pass directly into paruterine organ. 



Chapmania. — Larger worms with strong musculature. Genital 

 pores unilateral (in C. tauricolUs). Suckers armed. Cirrus- 

 sac not large. Eggs first developed in separate egg-capsules 

 and then passed into paruterine organ. 



SpliyroncJwUenia. — Larger worms with strong musculature. 

 Genital pores unilateral. Suckers unarmed. Cirrus-sac 

 not large. Eggs pass directly into paruterine organ f. 

 Many rows of hooks on rostellum. 



We may leave aside SjiJiyronchotcenia, which is clearly a 

 separate genus — not to be confounded with either Idiogenes or 

 Ohapmmiia. With regard to the two latter the differentiation 

 deducible from the above characteristics is altered to some extent 

 by the new facts recorded in the present communication. In the 

 first place, the cirrus-pouch of Chapmania is not particularly 

 small as is alleged by Ransom. I take it that the American 

 helminthologist has been misled by the absence of any statement 

 about the cirrus-sac of Chapmania in Fuhrmann's definition of 

 the genus, while, on the contrary, Idiogenes is defined by a large 

 sac. But the latter author, in his description of " Davainea 

 tatiricoUis" remarks + that the cirrus- sac reaches to the middle 

 of the proglottid, a statement which I confirm from my own 

 observations §. There is, therefore, here no difference between 

 Idiogenes and Chapmania. I have discussed above, in detail, the 

 statement that Chapmania diflers from Idiogenes in the fact 

 that the former genus shows a series of egg-capsules in which the 

 ova are imbedded before their transference to the pai-uterine 

 ■organ, and shown that there is no such difference between the 

 genera. There remains, thei^efore, merely the difierence of size 

 and the stouter build of Chapmania, Avhich is caused by the 

 relatively and actually greater thickness of the longitudinal 

 muscular layer of the body, to form a basis of distinction from 

 its ally Idiogenes. It is not at all impossible to regard these 

 facts as of generic value ; but it must be remembered that 



* Proc. U.S. Nat. Mus. vol. xl. 1911, p. 637. 



f This is to be inferred, as the actual transference was not seen in any of its 

 stages hy Ransom. 



J Rev. Suisse Zool. iv. 1896, p. 119. 



§ But the exact point to which the cirrus-sac reaches is affected by the degree 

 and direction of the contraction of the particular proglottid examined. It is 

 possible that the generic distinction has been chiefly founded upon Chapmania 

 tapica, where, according to Puhrmann (Swedish Exped. Egj-pt, pt. iii. p. 23), the 

 cirrus-sac hardlj' reaches the water vascular vessel. 



