ANNUARIO 
DEL 
MUSEO ZOOLOGICO DELLA R. UNIVERSITÀ DI NAPOLI 
( ISTiiova Serie ) 
VOLUME 3 . 
Num. 14. 25 Novembre 191U. 
WILLIAM NICOLL M. A., D. Se., M. B., Ch. B. 
Lister Institute ol Preventive Medicine 
(London) 
Oli Gasterostomum tergestinum Stossich. 
(1 incisione) 
[Ricevuto il li) Settembre 1U10] 
Amongst some specimens of Helicometra pulchella (Rud) ( = H. gobii Stoss. 
which were kindly sent to me by Professor Monticelli from Stossich’s collection, 
there was a single specimen of Gasterostomum tergestinum Stossich. On this fact 
being communicated to Professor Monticelli he very courteously placed a further 
collection of thè same species at my disposai. The form was first described by 
Stossich in 1883 x ) and apparently it has not been met with since. The speci¬ 
mens which 1 have examined do not entirely agree with Stossich’s originai de- 
scription and on that account a redescription has seemed desirable. 
The species is of small size, measuring *8 •—• l'3mm in length. and having a 
maximum breadth of • 5 — • 6 mm. The usuai dimensions are 1 x ’ 55 mm. The 
outline is most commonly ovai but occasionally it assumes thè form represented 
in Stossich’s figure and also in that which I have drawn here. Both figures how- 
ever represent thè animai more flattened than it actually is. The entire body is 
covered with regular scale-like spines, which are not absent even at thè posterior 
end, although they become sparse and somewhat irregular there. 
The anterior sucker is large and globular and is almost terminal. Its diameter 
is •20mm. It is very muscular and thè aperture is usually contracted. The sucker 
has no appendages. The mouth is situated a little in front of thè middle of thè 
') Stossich, M. — Brani di Elmintologia tergestina I.: Boll. Soc. Adriat. Voi. 8, 1883. Trieste , 
pag. 119, Tav. 2 , fig. o. 
