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but their secretary had suggested that a sketch of the family 

 Taeniidae, and more especially of the genus Hymenolepis (Wein- 

 land), on which the speaker had for some years past concentrated 

 his work, would probably be of greater general interest. Until 

 the time of the Danish naturalist and helminthologist Krabbe, 

 of Copenhagen, very few naturalists had made the life-history 

 and anatomy of avian tapeworms their particular study. It was 

 Krabbe who unravelled the tangled skein by gathering together 

 and differentiating the various species of avian tapeworms 

 enumerated and described since the days of Bloch, Pallas, Goeze, 

 and others in the latter part of the eighteenth century, and 

 Rudolphi, Oobbold, Pfaff, Berg, and others of later years who 

 had made, or were making, special study of avian eDtozoons. In 

 1869 Krabbe published a description of 123 species, with 313 

 figures, and in 1882 a second part, dealing with an additional 

 42 species, with 67 figures. Both these works are in Danish, 

 and have not yet been translated. Krabbe confined his attention 

 to the armed tapeworms of birds, and his drawings and measure- 

 ments of the various species are so accurate that the student 

 in helminthology who has Krabbe's Bidrag cannot fail to dis- 

 criminate and determine the species of Taenia he has under 

 consideration, of which he might be in doubt. Up to the time 

 of Krabbe and Weinland, tapeworms, with but one or two 

 exceptions, whether they were the guests of mammals, fishes, 

 reptiles, or birds, were classed as Taeniae', the genus Taenia was, 

 in fact, the " kitchen-midden " for the whole group. The first 

 to emphasise the necessity for the determination of species other- 

 wise than by the armature was Mequin, who, in 1880, said 

 that " every hookless Taenia has its armed species, and becomes 

 bookless by caducity, and devoid of a scolex by resorption." 

 Thus hookless or inerme tapeworms, according to Mequin, do 

 not exist. He also, in conjunction with Moniez, asserted that 

 there was a continuous development without change of host. 

 Thus they were opposed pari grada to Steenstrup's " Law of 

 Alternation of Generations." A translation into English of 

 Steenstrup's work was published by the Kay Society in 1845. 

 At the time Steenstrup formulated his law but little was known 



