57fi 



with such forms as TiUMiia solium of man. True*, other 

 authO'i's had recognized the great dill'ereuce iu soiiie 

 characters, but the group is such a ditiicult one to han- 

 dle that helminthologists, either from lack of time, 

 material, or courage, have carefully avoided any at- 

 tempt at a natural classification. 



Blanchard brought some order into the group iu 181)1 

 by proposing the new genera Davainea and Echino- 

 cotyle for certain forms, while Railliet followed up the 

 work by ]iropO'siiig the genera Drepanidotaenia Di- 

 crauotacuia, and Bothriotaenia for certain other forms. 

 These five new genera, together with Mesocestoides. 

 Ophryocotyle, Cotugnia, and Auiabilia enable us to 

 make a provisional classification by genera. It should, 

 however, be remembered that this classification is nec- 

 essaiily provisional in nature, as the internal anatomy 

 of these worms is as yet very poorly understood, and 

 a thoroug'h study of that subject will probably result 

 in great changes. 



Regarding the species it may be again remarked 

 that a considerable number of different forms have 

 I)een described, but that a number of these species will 

 unquestionably fall, while new species will have to 

 be described for forms whicli are not yet recognizable 

 as distinct. 



ANALYTICAL KEY TO FAMILIRS AND GENERA 



/ Head with two elongated 

 grooves or slit-like suck- 

 ers; rostellum wanting; 

 uterus with special pore; 

 genital pores generally- 

 dorsal or ventral BOTHRIOCEPHAT.IDAK. p. 579 



^•■^ Head with four cup-shaped 

 suckers; rostellum pre- 

 sent but not always evi- 

 dent; utejus without any 

 special pore; genitMl pores 



generally n^arginal T.-M'^.NlIDAIi], p. oS4 



>• Head is Calways?) absent. 



