NO. 2258 TAENIOID CEST0DE8 OF DOGS AND CATS— HALL. 3 



ganglia. The excretory system consists, commonly, of a dorsal and 

 a ventral excretory vessel on each side of the strobila with a simple 

 or elaborate set of vessels connecting the vessels of the same side or of 

 opposite sides. The main longitudinal vessels terminate in open- 

 ings in the posterior extremity of the strobila and receive waste 

 matters poured in from canaliculi originating in flame-cells in the 

 parenchyma. With rare exceptions, the strobila is hermaphroditic, 

 the male and female sex organs being represented in each segment. 

 The eggs, or, more properly, embryophores, develop in the segments 

 to form an onchosphere armed with three pairs of hooks and sur- 

 rounded by one or several membranes, or they are similar to fluke 

 eggs, often with an operculum, do not contain an embryo when they 

 escape from the segments, and later develop an onchosphere with a 

 surrounding covering of cilia. Development always involves an al- 

 ternation of generations, the intermediate stage, in the form of a 

 bladderworm of some sort and with the developed head of the adult 

 as the essential structure and a surrounding membrane of some sort 

 as the incidental structure, developing in an intermediate host. This 

 larval stage develops to the adult worm on ingestion by a suitable 

 host. 



Superfamily TAENIOIDEA Zwicke, 1841. 



Synonym. — Cyclophyllidea van Beneden. 



Superfamily diagnosis. — Cestoda: Head or scolex with four cup- 

 shaped suckers which may exceptionally (Tetrabothriidae) bear au- 

 ricular appendages, or exceptionally (Fimbriariidae) with a pseudo- 

 scolex in place of this scolex. Apical rostellum present or lacking. 

 Suckers and rostellum may be armed with hooks or unarmed. Neck 

 present or lacking. Strobila with well-developed segmentation, or 

 exceptionally (Fimbriariidae) without division into segments. A 

 single series of reproductive organs or a complete or incomplete dou- 

 ble series, both male and female organs present in the same segments 

 except in Dioicocestus where the strobilae are, respectively, male or 

 female. Genital pores usually present and marginal, exceptionally 

 ventral (Mesocestoididae), or lacking (Aporina). Testes usually 

 numerous, occasionally as few as two, and in medullary portijon of 

 segment. Ovary more or less bilobed. Yolk gland compact, usually 

 single and located near the median line. So-called shell-gland be- 

 tween ovary and yolk gland. Uterus v.ithout special opening for the 

 discharge of eggs to the exterior, except that rarely a secondarily 

 formed aperture may be present. Onchosphere with one or several 

 membranes and Avithout operculum. Larval stages in vertebrates or 

 invertebrates. Adults in the alimentary canal of vertebrates. 



Type-family. — Taeniidae Ludwig, 1886a. 



In limiting the scope of this paper to a consideration of the taenioid 

 cestodes, there have been excluded from consideration the carnivore 



