304 PROF. W. J. DAKIN ON THE 
GLEPIDURUS ViIRIDIS Baird, var. ELONGATUS Wolf. 
Specimens occur regularly every year about July and August 
in very shallow, muddy pools on a road at Northam. 
The characteristic carapace covering all the segments of the 
body and only allowing a glimpse of the caudal rami enables one 
to recognise the similar ity to Wolf’s specimens. 
The number of segments not bearing legs is as usual, five. The 
length of my specimens averaged about 28 mm. without the 
caudal appendages, and these brought the total length to 53 mm. 
This size is greater than that of the largest of Wolf's specimens. 
LEPIDURUS VIRIDIS. 
A large number of specimens of Lepidurus has been obtained 
from waters at T'iammin, Western Australia. These individuals 
are certainly not Wolf’s variety Lepidurus viridis var. elongatus, 
and still more certainly not his variety setosws. They may be 
described as follows :—The large examples average about 20 mm. 
for length of carapace, with a total length of 40 mm. counting the 
long anal furea. 
The carapace is broadly rounded in front and somewhat 
considerably vaulted behind, with a prominent keel down the 
middle lir The posterior notch in the carapace is practically 
semicircular. 
The long axes of the eyes run at an angle to each other to 
meet anteriorly. The anterior and posterior margins of the 
erescentic eyes are of similar shape and extent. 
The “ Nackenorgan” projecting between the two eyes and 
slightly posterior is circular in shape. 
lt seems undesirable to name these specimens anything but 
the simple Lepidurus viridis. From the difficulty of recognising 
varieties it would appear that a comparative study of the genus is 
required. This could only be carried out successfully with a very 
large collection of individuals from many localities in different 
parts of the world. 
EXPLANATION OF THE PLATES. 
Prats I. 
Branchinella australiensis, var. occidentalis, noy. 
Fig.1. Male specimen. X 1°5. 
2. Head and appendages of male. X 3°5. 
3. Antenna or “clasper” of male.  X 5. 
4. Surface of antenna considerably enlarged. 
5. 4th trunk-limb of male. X 6. 
Branchinella northamensis, sp. n. 
Fic. 6. Posterior segments and caudal rami. % 10. 
7. Genital segments bearing ovary. X 10. 
8. Head and appendages of female. xX 8. 
