THE TASMANIAN NATURALIST. 
Fig. 1. Two parasites attached to tip of tongue. 
Fig. 2. View of parasite from above. 
Fig. 3. Side view of parasite. 
(All greatly enlarged.) 
‘the microscope. They are not found 
upon every lly, and are commoner upon 
Alarch-flies than blow-flies, but a March- 
fly has seldom more than three or four on 
its proboscis, while a blow-fly may have 
ten or a dozen. During the middle of 
summer nearly every Alar eh-lly had one 
or more, and they were ccommon on 
blow-flies, but in May, when my last 
specimens were taken, 1 only found one 
Iblow-fly that iud them out of about 50 
I examined. It had eleven. The micro¬ 
scopic measurements of Uiese parasites 
are as follow:—Length (exclusive of 
bristles), 1941 microns; length of head, 
<13 microns; greatest width (to edge of 
segments), 111) microns. The length, 
making allowance for alterations pro¬ 
duced hy pressure of cover-glass, was 
very similar in all specimens. It may 
he mentioned that a micron is the unit 
adopted for microscopic measurements. 
It equals the one-thousandth part of a 
millimetre, or, roughly, the 25,00(>th part 
of an inch. Fig. 1 shows the tip of a 
blow-fly's proboscis, with two of the para¬ 
sites fastened to the pseudo-tracheae, en¬ 
larged GO diameters. Fig. 2 shows a 
hack view of one of the parasites detadj- 
ed, and magnified 280 diameters. The 
hooks are seen through the semi-trans¬ 
parent shell of the head. Fig. 3 is a 
view of another turned upon its side, giv¬ 
ing an oblique view of the under surface 
of the head. It is enlarged 500 dia¬ 
meters. TV i» hooks, tube, and hood-like 
arrangements are shown. In some 
specimen the ventral edges of the ab¬ 
dominal segments are produced into long, 
wavy filaments, but 1 have reserved this 
appearance, which may possibly bo a 
sexual characteristic, for further study. 
The life-history and family connections 
of the creature are quite unknown to 
me, and T would he very much obliged 
to any reader of t<«is journal who could 
supply information regarding it. 
The Tasmanian t ook cod is attacked by 
one of the most remarkable parasites 
known, and belonging to the genus Ler- 
naea. This creature fastens itself to the 
cod by a three-hooked head; from this I 
( 9 ) 
there extends a long thin neck with a 
stout curved body, from which extend 
two white appendages exactly like spiral 
springs. The parasites themselves are 
often covered with a species of zoophyte. 
