51 
Medical significance. — Probably a purely accidental parasite for 
man, more likely to occur in children. The worms have a tendency 
to burrow into the intestinal mucosa, making a tunnel-like channel, 
through which the segments are pulled much like a train of cars pass- 
ing through a tunnel. 
Prevention. Children should not be allowed to play with dogs and 
cats that are infested with fleas and lice. 
Genus HYMENOLEPIS« Weinland, 1858. 
Generic diagnosis. — Dipylidiinse (p. 48) : Head generally small; rostellum retractile 
well developed and armed, or rudimentary and unarmed; suckers usually unarmed. 
Genital pores single, marginal, unilateral. Testes few; usually three in each seg- 
ment. Uterus saclike; often filling the segment; frequently with outpocketings and 
incomplete partitions. Eggs with two, three, or four membranes, the inner of which 
closely invests the embryo and may exhibit a small mammillate projection at each 
pole; the outer membrane is separated from the inner by a wide intervening space. 
Larva a cercocyst or staphylocyst. 
Type species. — Hymenolepis fiavopunctata Weinland, 1858 = 7/. diminula (Rudolphi, 
1819). 
KEY TO THE SPECIES OF HYMENOLEPIS REPORTED FOR MAN. 
(For species thus far found in man in the United States, follow roman type.) 
Strobila small, 5 to 45 mm. long by 0.5 to 0.9 mm. wide, filiform; head armed 
with a crown of 20 to 30 hooks; eggs generally oval, with filaments 
attached to the poles of the inner membrane; common . Hyrrt' nolepis nana (p. 51) 
Strobila 10 to 60 mm. long by 2.5 to 4 mm. wide; head unarmed; eggs gen- 
erally round, prominent intermediate layer of albuminous substance 
between outer and inner membranes, outer membrane frequently with 
radial striations; rare in man Hymenolepis diminuta (p. 54) 
Strobila lanceolate, 30 to 130 mm. long by 5 to 18 mm. broad; head small, com- 
pared with strobila, armed with 8 to 10 hooks; eggs oval, without filaments on 
the inner membrane; very rare in man Hymenolepis lanceolata (p. 58) 
The Dwarf Tapeworm— HYMENOLEPIS NANA & (Siebold, 1852) Blanchard, 
i8gi. 
[Figs. 81 to 87.] 
Specific diagnosis. — Hymenolepis (p. 51): Strobila 5 to 45 mm. in length, 0.5 to 
0.9 mm. in maximum breadth, composed of about 100 to 200 segments. Head sub- 
globular, 130 to 480/< in diameter; rostellum well developed, freely movable, armed 
with a single crown of 20 to 30 hooks, 14 to 18/* in length; suckers globular, 80 to 
150/f in diameter. Neck long. Anterior segments very short; following segments 
a Synonyms. — Hymenolepis Weinland, 1858; Diplacanthus Weinland, 1858 (not 
Agassiz, 1842, fish); Lepidotrias Weinland, 1858; “ Hymenolepsis” of Osier, 1895, 
and other authors (misprint); ‘ ‘ Diplacanthus ’ ’ of Cohn, 1899 (misprint). 
b Synonyms. — Ticnia murina Dujardin, 1845a (not T. murina Grnelin, 1790a =Cysti- 
cercus fasciolar is Rudolphi); Tsenia nana Siebold, 1852, not (van Beneden, 1858) 
Diesing, 1861a; T. segyptiaca Bilharz; 1852, not Krabbe, 1869; T. nania Kuechen- 
meister, 1855, misprint for nana; Diplacanthus nanus (Siebold, 1852) Weinland, 1858; 
Tsenia ( Hymenolepis ) nana Siebold of Leuckart, 1863; T. “rafi a” of Bell, 1886b (mis- 
print); Hymenolepis nana Blanchard, 1891a; II. murina Blanchard, 1891a; “ Hymen- 
olepsis ” nana of Osier, 1895, and other authors (misprint); Tsenia “ minima ” of 
Huber, 1896a (misprint for T. murina). 
Bibliography. — For medical and zoological discussion of this species, with compi- 
lation of 106 cases, see Ransom, 1904. 
