54 
The Yellow Spotted Tapeworm — HYMENOLEPIS DIMINUTA'/ i Rudolphi, 
i8ig) Blanchard, i8gi. 
[Figs. 88 to 95.] 
Specific diagnosis. — Hymenolepis (p. 51): Strobila 10 to 60 nun. in length, 2.5 to 
4 mm. in maximum breadth; composed of 800 to 1,300 segments. Head small, 
almost globular; 200 to 600// in width; rostellum rudimentary, pyriform, only 
slightly protractile; hooks absent; suckers globular, near the apical portion of the 
head, 80 to 160/4 in diameter. Neck usually short. Segments throughout strobila 
broader than long. Genital pores on left margin, near the junction of the anterior 
and middle thirds of each segment. Three testes in each segment; vas deferens 
dilates into a prominent seminal vesicle before entering the cirrus pouch, within 
which also is a vesicle. Gravid uterus occupies most of the proglottids; its cavity is 
subdivided into a large number of incompletely separated compartments filled with 
eggs. Eggs round or slightly oval; outer membrane 54 to 86/4 in diameter, yellowish 
in color, may be radially striated; inner membrane 24 by 20/4 to 40 by 35/4 in diameter, 
with mammillate projection at each pole often not apparent; between outer and 
inner membranes a prominent third layer of albuminous substance, often appearing 
as two delicate smooth membranes, with intervening space filled by a granular 
coagulum; embryonal hooks 11 to 16/4 in length. 
Habitat. — Adults in small intestine of brown or Norway rat ( Mus decumanus ) , 
black rat (M. rattus), house mouse ( M . musculus ), Egyptian or roof rat (9/. rattus 
atexcindrinus), wood or field mouse (M. sylvaticus ), Ilhipidomys pyrrhorh inus [accord- 
ing to Linstow, 1878a, 23], and man ( Homo sapiens). 
Development. — The larval stage ( Cercocystis II. diminutse) occurs in larval and 
adult meal moths ( Asopia farinalis ); in young and adult earwigs {Anisolabis annidi- 
pes ); and in adult beetles (Acis spinosa and Scaurus striatus). 
Geographic distribution. — Massachusetts, Pennsylvania, Nebraska, Iowa, District 
of Columbia, Maryland, Brazil, Italy, Germany, France, Austria. 
Medical significance.— A rare and probably- accidental parasite of 
man; easily expelled. 
a Synonyms. — Taenia diminuta Rudolphi, 1819a; T. leptocephala Creplin, 1825a; 
Hymenolepis flavopunclaia Weinland, 1858; Tania ( Hymenolepis) fiavopunctata Wein- 
land, 1859; II. ( Tepid oiri as) fiavopunctata 'Weinland, 1861; T. fiavornaculata Leuckart, 
1863; T. “ flavopuncta” Cobbold, 1864b (misprint); T. “Jlaviopunctdta” Vogt, 1878 
(misprint); T. “ flavopunktata” Stein, 1882; T. varesina E. Parona, 1884; T. minima 
Grassi, 1886; T. “ septocephala ” Perroncito & Airoldi, 1888 (misprint); Hymenolepis 
diminuta (Rudolphi, 1819) Blanchard, 1891a; “ Hymenolepsis ,, fiavopunctata of Osier, 
1895, and other authors (misprint); T. “ varerina ” Huber, 1896a (misprint for 
T. varesina ); T. ‘ 1 flavapunclata ’ ’ Simon, 1896 (misprint); T. ‘ ‘ leptocefalu ’ ’ Previtera, 
1900; T. 11 ceptocephala ” Lussana & Romaro [? date] (misprint); Tenia fiavopunctata 
(Weinland, 1858) Packard, 1900. 
Bibliography. — For medical and zoological discussion of this species, with com- 
pilation of 10 cases, see Ransom, 1904. 
