NOTES ON THE HISTEIOBDELLIDiE. 
197 
Notes on the Histriobdellidae. 
By 
W. A. Harwell, M.A., D.Sc., F.R.S., 
Challis Professor of Biology, University of Sydney. 
With Plates 11 — 14 and 1 Text-figure. 
Inteoductoey. 
The publication by Shearer iu 1910 of an elaborate account 
of the anatomy of Hi striob della liomari (9) has greatly 
added to our knowledge of that remarkable and interesting 
animal, which had remained neglected, so far as published 
work is concerned, since 1884, when Foettinger published 
his valuable observations on it (3). 
In 1900 I published (6) an account of an allied fresh- water 
form — Stratiodrilus t as manic us — which I found in the 
gill-cavities of freshwater crayfishes in Tasmania. Some 
years ago I found another member of the same group 
inhabiting the gill-cavities of Astacopsis serratus in 
streams at elevations of 2000 to 3000 feet in the Blue 
Mountains of New South Wales; and I have since found 
specimens of the same form on crayfishes from creeks of 
various other parts of the same river-system (the Hawkes- 
bury) — the Cataract River and the Loddon River — from small 
streams flowing directly into the sea on the coast of Illawarra, 
at Port Hacking (Waterfall Creek, a branch of the Port 
Hacking River), creeks running into Middle Harbour, Port 
Jackson, and at Pitt Water off Broken Bay (mouth of the 
Hawkesbury). I have also found it in the large crayfishes 
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