14 
Development. — The lars^al stage ( Cercocystis H. diminutse) occurs in larval and adult 
meal moths {Asopia farinalis) ; in young and adult earwigs {Anisolahis annulipes) ; and 
in adult beetles {Acis spinosa and Scaurus striatus). 
Geographic distribution. — Massachusetts, Pennsylvania, Nebraska, Iowa, Dis- 
trict of Columbia, Maryland, Brazil, Italy, Germany, France, Austria. 
The Lanceolate Tapeworm — HYMENOLEPIS LANCEOLATA« (Bloch, 1782) 
Weinland, 1858. 
Specific diagnosis. — Hymenolepis: Strobila lanceolate, 30 to 130 mm. long, by 5 to 
18 mm. broad. Head compared with strobila very small ; rostellum protractile, armed 
with single row of 8 hooks, 31 to 35 p long. Neck short, often retracted with 
head into anterior portion of strobila. Segments much broader than long through- 
out the strobila. Genital pores on right-hand margin of segment near anterior 
border. Three testes in each segment; vas deferens enlarged to form a seminal ves- 
icle, frequently S-shaped, before entering cirrus pouch; within latter, a second vesicle; 
vas deferens describes a complete loop in cirrus pouch before being transformed into 
the cirrus; cirrus freely protrusible, armed with spines. Female organs on opposite 
side of segment from genital pore; gravid uterus sac-like, with out-pocketings, filling 
most of the segment. Egg oval or spherical, with two thin membranes separated by 
an intervening space containing a small amount of albuminous substance; inner 
membrane occasionally with polar papillae; outer membrane 50 by 35 y to 100 by 
100 yu in diameter; inner membrane 30 by 25 p to 40 by 25 p in diameter; embryonal 
hooks 8 to 15 yu in length. 
Habitat. — Adults in intestine of tame duck boschas domestica) ; black duck 
{Anas obscura) ; tame goose {Anseranser domesticus) ; muscovy duck ( Cairina moschata) ; 
white-headed duck {Erismatura leucocephala) •, pochard {Aythya ferina) ; African 
teal {Aythya nyroca) ] red-crested pochard {Aythya rufina); flamingo {Phoenicopterus 
roseus). Zschokke (1902) has recently reported one case in man {Homo sapiens). 
Development. — Not experimentally determined. Larval stage probably lives in 
small fresh-water Crustacea. 
Geographic distribution. — England, Denmark, France, Germany, and Austria. 
The Dwarf Tapeworm — HYMENOLEPIS NANA (Siebold, 1852) Blanchard, 1891. 
^ HISTOKICAL REVIEW. 
Hymenolepis nana was first discovered in man by" Bilharz in 1851 at 
Cairo, Egypt, and the next year Siebold (1852) published a descrip- 
tion, based upon letters from the discoverer, which translated reads as 
follows: 
Tsenia nana Sieb. ^ — It will not surprise us that among the many helminths which 
are found in man in the Nile countries there is also a special tapeworm. Bilharz 
discovered such a one and wished to call it after its native country, Tsenia segyptiaca; 
« Synonyms. — Tsenia anserum Frisch, 1727 [according to Rudolphi, 1810]; T. anseris 
Bloch, 1779 [according to Rudolphi, 1810]; T. lanceolata Bloch, 1782 (not T. lanceo- 
lata Chabert; not T. lanceolata Rosseter, 1891) ; T. acutissima Pallas, 1781, in part; 
T. lanceola Batsch, 1786; Halysis lanceolata (Bloch, 1782) Zeder, 1803; Hymenolepis 
{Dilepis) lanceolata (Bloch, 1782) Weinland, 1858; Drepanidotsenia lanceolata (Bloch, 
1782) Railliet, 1892; Hymenolepis {Drepanidotsenia) lanceolata Cohn, 1899; Tsenia- 
Drepanidotsenia lanceoWa (Bloch) Dadai, 1900. 
^Tsenia nana Sieb. — Es wird uns nicht iiberraschen, dass unter den vielen Hel- 
minthen, -welche in den Nillandern den Menschen bewohnen, sich auch ein besonderer 
Bandwurm befindet; Bilharz hat einen solchen entdeckt und nach seinem Vaterlande 
