JOUK. Kov. SOC. 'WESTERN' AUSTRALIA, VOL. XII, Xo. 1-). 183 
Cditril)iitions fiom the Dejjavtnieiit of Bi('logy iu the Viuvevsity 
of Western Australia. Xo. 7. 
I 
A Description of Two New Species of Acrotelsa by Professor 
G. E. Nicholls, D.Sc.. F.L.S., and K. C. Richardson, B.Sc. 
{Head July 13, 1933. PuhlUlird August 2, 1926.) 
The only work which lias apiieared, hitherto, dealinj>' with thu 
Thysanura of Wh’stevii Australia, is that of Bilvestri (1907), who 
descriheil a eiJlection made by the Hambui'g- Expedition in 1903 
under l)rs. Miehaelsen and Haitmeyer. Silvesti'i states that al- 
tliough Western Australia was at one time regarded as almost 
locking in Thysanura, no fewer than sixteen species were represent- 
ed in this collection, fifti'en being referable to the family Le])is- 
matidae and one to the Jaiiygidae. Of tiie former, tw'elve species 
]»roved to be new, and for one a nerv genus (Trineniura) was estab- 
lished- Of the fifteen genera of Lepisiuatidae mentioned by 
Escheriscli iu his monograph on the group, the genus Acrotelsa, to 
■\diich belong the two new species here described, is almost cosmo- 
]K)litan. It is of interest that the first Thysanuran recorded from 
Australia was a sjteciinen of tlu' geiiue (Ac)'otcli^a pi'oducia ) from the 
Pe:ik DoAvns in Queensland. 
The classification of this family is based largely on the follow- 
ing characters The distril)ution of the setae ami the tufts of setae 
or combs; the shai)e (tf the tenth tergite and the arrangement of 
the setae thiu-eon; the number of abdominal styles, and the form of 
the gimital a])i)('ndages, body scales and ])al}>s, \e)’y litth' iin- 
jM'vtaiU'e seems to have been attached to the structure of the mouth 
parts, }ierha])s because of the general similarity that exists between 
those of the different sjiecies and of the difficulty of dissection. In 
this contribution an endeavour has been made to give a more com- 
idete desci-iption of the a])])endages, with a vieAv to assisting in 
iilentification, though diffeiannu's iu tlu' structure ar(‘ not ahvays 
very marked in clos(dy related forms, Silvestri has attached im- 
jiortance to tln^ metasternite, both as to its form and the arrange- 
ment of the setae upon it. An account is here given of the con- 
tiition of the mesosternit(‘ as furnishing a furtluu- aid to identifica- 
tion. 
The specimens described form jiart of the collection of the 
