212 THE ANIMAL PARASITES OF MAN 



THE CLASSIFICATION OF THE CESTODES. 



The classification of the Cestodes, like that of the Trematodes, has so far 

 been undertaken by a number of investigators, but has not yet been definitely 

 concluded. The genera, numbering about eighty, are classified in the following 

 manner : 



I. Bothriocephaloidea. Scolex armed or unarmed, with two usually slightly 

 developed groove-like suckers on the flat surface ; the external segmen- 

 tation may be absent or distinct ; three genital orifices ; the genitalia 

 rarely duplicated ; numerous follicles of vitellaria, situated in the 

 lateral field and mostly in the cortical layer. The eggs are similar to 

 those of the Fasciolidea, but do not always possess a lid. 



Fam. i. Dibothriocephalidfs . The suckers are variously developed : 

 by coalescence of the free borders they may be transformed into 

 suctorial tubes, or may be replaced by a cephalic suctorial organ. 

 The uterus forms a rosette ; eggs are provided with lids. 



(1) Subf. Ligulines (Ligula, Schistocephalus}. 



(2) DibothriocephalincB (Dibothriocephalus , Diplogonoporus, &c.). 



(3) Cyathocephalince (Diplocotyle, Cyathocephalus, Bothrimonus}. 



(4) ' TricBnophorince (Fistulicola, Ancistrocephalus, Trianophorus , 



&c.). 



Fam. 2. PtycHobothriida. Scolex unarmed ; the uterus does not form 

 a rosette, but presents a spacious uterine cavity. The eggs have a 

 thin shell and no lid. 



(1) Subf. Amphicotylince (Amphicotyle , Abothrium, &c.). 



(2) Ptychobothriince (Ptychobothrium, &c.). 



Fam. 3. Amphitretidce. Vitellogene gland in the medullary layer ; uterus 



with cavity ; eggs with thin shells without lids (Amphitretus, &c.). 



II. Tetraphyllidea. Scolex armed or unarmed, with four very motile 



pedunculated or sessile bothridia, or with four round suckers ; segmentation 



always distinct ; no uterine orifice ; the cirrus and vagina open at the 



border ; the follicles of the vitellaria in the side fields or at the borders, 



in the cortical layer. Eggs thin-shelled ; no lid. 



Fam. i. Onchobothriidce. There are always hooks in the sessile or 

 pedunculated bothridia, in addition to accessory suckers or areoles 

 (Onchobothrius , Calliobothrium, &c.). 



Fam. 2. Phyllobothriidce . Bothridia mostly pedunculated, simple, or 

 with accessory suckers or areoles, always without hooks (Antho- 

 bothrium, Phyllobothrium}. 

 Fam. 3. Ichthyotceniidce. With four suckers, mostly unarmed (Ichthyo- 



tcBnia). 



III. Cyclophyllidea. Scolex with four suckers, between which an apical 

 rostellum may be present ; hooks on the rostellum, rarely on the 

 suckers ; segmentation almost always distinct ; no uterine orifice ; 

 cirrus and vagina usually open at the border ; genitalia rarely dupli- 

 cated ; vitellogene gland single, usually placed behind the ovary ; eggs 

 thin-shelled, without lids ;~^oncospheres with one or several integuments. 



