4 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 55. 



tapeworms belonging to the Proteocephalidae and the Diphylloboth- 

 riidae. The only species of Proteocephalidae reported from car- 

 nivores is Ophiotaenia punica (Kholodkovski, 1908) La Rue, 1911. 

 This species was described from the dog by Kholodkovski (1908) as 

 Taenia punica^ but the present writer (Hall, 1910) pointed out that 

 this should be transferred to the genus Proteocephalus and that it 

 was presumably not a true parasite of the dog, but had been ingested 

 by the dog in eating the true hjost, some fish, reptile, or batrachian. 

 In his revision of the Proteocephalidae, La Rue (1911) created tho 

 new genus Ophiotaenia for the reptilian cestodes of that family, and 

 transferred this species to the new genus. This species is evidently 

 not to be considered as a parasite of carnivores and nothing would be 

 gained so far as concerns the purposes of the present paper by a de- 

 scription of its morphology. The presence of follicular yolk glands 

 in the lateral fields is one feature which distinguishes the Proteo- 

 cephalidae from the Taenioidea. 



The omission of the Diphyllobothriidae from this paper is of more 

 importance than the omission of the Proteocephalidae. Species be- 

 longing in this group have been reported from carnivores in North 

 America and material of the sort is available to the writer for study, 

 but a casual examination of the material indicates that it would 

 require more time for adequate study than can be given at present. 

 This family is relatively much less important than the superfamily 

 Taenioidea covered in this paper. Members of the Diphyllobothrii- 

 dae are characterized by the presence of a rosette-shaped uterus which 

 has a special aperture in the midventral line for the discharge of eggs. 



The keys given deal with each taxonomic group, from families to 

 the species of a given genus, separately. At the end of this paper is 

 a key covering the species of all genera involved. 



KEY TO THE FAMILIES OF TAENIOIDEA. 



1. Genital pores located on the ventral surface near the median line. Eggs In 



gravid segments enclosed in a single thick-shelled egg capsule. 



MESOCESTOIDIDAE, p. 59. 



Genital pores lateral. Eggs in gravid segments contained in a uterus or 



in numerous egg capsules 2 



2. Usually large forms. Genital pores irregularly alternate. Rostellum usually 



well developed and usually armed with a double crown of hooks, rarely 

 with a single (?) crown of hooks or unarmed. Suckers unarmed. Uterus 

 with a median stem and lateral branches. Eggs thick shelled — i. e., 



embryo sun-ounded by a thick embryophore TAENIIDAE, p. 5. 



Usually small forms. Genital pores single or double; if single, regularly 

 or irregularly alternate. Rostellum present or absent; if present armed 

 with one to numerous rows of hooks. Suckers armed or unarmed. Uterus 

 saclike and persistent or with one or several parauterine organs to which 

 the eggs pass in the final stage of development. Eggs with thin transparent 

 shells (i. e., embryo surrounded by thin transparent embryophores). 



HYMENOLEPIDIDAE, p. 61. 



