HYMENOLEPIS DIMINUTA 



229 



2. Hymenolepis diminuta, Rud., 1819. 



Syn. : Tcenia diminuta, Rud., 1819; T. leptocephala, Crepl., 1825; 

 T. ftavopunctata, Weinld., 1858; T. varesina, E. Parona, 1884; 7\ minima, 

 Grassi, 1886. 



This species measures 20 60 cm. in length, and up to 3-5 mm. in 

 breadth ; there are from 600 to 1,000 segments. The head is very 

 small (o'2 0*5 mm.) ; it is club-shaped and has 

 a rudimentary unarmed rostellum ; the neck is 

 short ; the mature segments are 3-5 mm. in 

 breadth, o'66 mm. in length; the eggs are round 

 or oval (0-060 0-070 : 0*070 0*086 mm.). The 

 egg-shell is yellowish and thickened, with indis- 

 tinct radial stripes ; embryonal shell double, thin ; 

 the outer one is somewhat pointed at the poles ; 

 oncosphere 0^028 0^036 mm. 



Hymenolepis diminuta lives in the intestine of 

 rats and mice : Mus decumanus,* the sewer rat ; 

 M. rattus, the house rat, M. musculus, the mouse, 

 and M . alexandrinus ; it is occasionally also found 

 in human beings. 



Weinland described it from specimens col- 

 lected by Dr= E. Palmer in 1842, in Boston, 

 from a child aged 19 months, as T. flavopunctata. 

 A second case was only reported in 1889 by 

 Leidy relating to a three-year-old child from Phil- 

 adelphia ; a third case was simultaneously reported of a two-year- 

 old girl in Varese (T. varesina), and Grassi described another case 



FIG. 156. Hy- 

 menolepis diminuta, 

 scolex magnified. 

 (After Zschokke.) 



FIG. 157. Hymenolepis diminuta ; two pro- 

 glottides slightly enlarged. (After Grassi.) 



FIG. 158. Ovum of Hymeno- 

 lepis diminuta ', greatly magni^ 

 fied. (After Grassi:) 



relating to a twelve-year-old girl from Catania (Sicily). Sonsino 

 and Previtera reported the same species in Italy, Zschokke in 

 France, Lutz and Magalhaes in South America, and Pachard in 

 North America. 



According to Grassi and Rovelli the cysticercus stage lives in 



