62 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 55. 



of reproductive organs in each segment. Genital pores marginal and 

 bilateral, unilateral, or regularly or irregularly alternate. Eggs with 

 thin transparent shells. Adults in mammals, birds, reptiles, and 

 amphibia. 



Type-genus. — Hymenolepis Weinland, 1858a. 



Subfamily Dipylidiinae Stiles, 1896. 



Synonyms. — Ehynchotaenia Diesing, 1850«; Malacolepidota Wein- 

 land, 1858a; Cystoideae Leuckart, 1863; Cystoidei Leuckart, 1886; 

 Cystoidotaeniae Eailliet, 1885a; Microtaeniae Claus, 1891; Dipyli- 

 dinae Eailliet, 1896; Hymenolepinae Perrier, 1897a; Dilepininae 

 Fuhrmann, 1907 ; Dilepidinae Eailliet and Henry, 1909. 



Subfamily diagnosis. — Hymenolepididae : Eostellum armed or, less 

 frequently, lacking. Suckers unarmed. A single set or, less fre- 

 quently, a double set of reproductive organs in each segment. 

 Uterus sac-like, simple or lobulated, or not persistent, breaking down 

 into numerous egg capsules, each containing one or several eggs. 

 Parauterine organs not developed. Adults in- mammals, birds, and 

 i-eptiles. 



Type-genus. — Dipylidium Leuckart, 1863. 



Genus DIPYLIDIUM Leuckart, 1863. 



Synonyms. — Taenia Linnaeus, 1758a, part, of authors; Taenia 

 {Dipylidium) Leuckart, 1863; Alyselminthus Weinland, 1858a, not 

 Zeder, 1800a; Cryptocystis Villot, 1882; Microtaenia Claus, 1884; 

 Depylidium Sonsino, 1895; Dypilidium Castellani and Chalmers, 

 1910; BipyUduin Daniels, 1910. 



Generic diagnosis. — Dipylidiinae: Eostellum armed with several 

 circlets of hooks which are of rose-thorn shape and usually provided 

 with a discoidal base. Suckers unarmed. A double set of reproduc- 

 tive organs in each segment. Genital pores double and opposite. 

 Testes very numerous, scattered throughout the entire medullary 

 parenchyma. Vas deferens coiled; vesicula seminalis lacking. 

 Gravid segments usually longer than broad. Uterus at first reticular, 

 later breaking up into egg capsules, each containing one or more eggs. 

 Adults in mammals and birds. 



Type-species. — Dipylidium caninum (Linnaeus, 1758a) Eailliet, 

 1892v. 



KEY TO SPECIES OF DIPYLIDIDM. 



1. Strobila not over 25 mm. long ; rostellum with 4 circlets of hooks, the hooks 



45 II long and with a handle and guard ; the cirrus pouch opens ventral of 



the vagina ; 1 egg to each capsule DipyUdium trinchesei, p. 69. 



Strobila 5 cm. long or longer; hooks rose-thorn-shaijed 2. 



2. Head with 16 circlets of hooks; strobila 20 to 30 cm. long; 1 egg to each 



egg capsule Dipylidium pasqualei, p. 71. 



Heads with 3 to 14 circlets of hooks 3. 



