1906-7.] Hydrachnidse collected by the Lake Survey. 305 
the entomostracan to support, the hydrachnid does not appear to have 
its movements hampered, as it moves about as freely as before, sometimes 
throwing itself on its back, with its long slender limbs waving above, and 
then, with a sudden jerk, bounding off to another place. When sufficient 
nutriment has been absorbed, the palpi are relaxed and the body of the 
victim released. 
The second and third pairs of limbs are used mainly for locomotion, the 
first pair being held up in front, and the fourth pair apparently trailed 
behind. Occasionally this order is changed, so that the third and fourth 
pairs of limbs are used for progression, the second pair being waved about 
in the water, and the first pair still remaining raised up in front. 
Instead of swimming with an easy, regular motion, this hydrachnid 
rather jerks itself through the water, sometimes forwards, sometimes back- 
wards, and it appears to swim as much with the ventral surface upwards 
as with the dorsal. 
10. Genus NEUMANIA, Lebert. 
Neumania vernalis, Mull. — Found by Mr Scourfield near Fort Augustus, 
August 1903. 
11. Genus HUITFELDTIA, Sig Thor. 
Huitfeldtia rectipes, Sig Thor. — Specimens were found by Mr Murray 
at Hundland, Boardhouse, Housby, and Swanney, in the Orkney Islands. 
As there was no record of this hydrachnid having been found before in 
Britain, I sent specimens of the male and female to Dr Thor for verifica- 
tion. He confirmed my identification, and stated that he had not known 
of the occurrence of this species except in Norway. 
Mr Soar has drawn the figures which show the details of this species. 
The following are the measurements given by him, as well as those given 
by Dr Sig Thor : — 
Female : — 
C. D. Soar. 
Sig Thor. 
Length ..... 
1*40 mm. 
1-20 mm. 
Breadth 
. 1*12 „ 
POO „ 
Length of Mandible . 
•25 „ 
Length of Palpus 
. -40 „ 
•27 „ 
Length of bristle on Palpus 
•16 „ 
Legs, 1st pair .... 
1*15 „ 
„ 2nd „ .... 
1-27 „ 
„ 3rd „ .... 
1-30 „ 
,, 4th ,, .... 
1*40 „ 
Distance apart of double eyes 
Male : — 
•26 „ 
Length ..... 
• f24 „ 
Breadth ..... 
. -98 „ 
Length of Genital Area 
VOL. XXVII. 
• *19 „ 
20 
