182 
HORN EXPEDITION—MOLLUSCA. 
described as Thersites dydonigera, and Helix^ n.sp., herein described as Angasella 
papulosa ] the third species, which is Angasella setigera (milii), is represented by a 
single bleached example. 
Mr. J. East, who was attached to an exploring party which visited the eastern 
part of the McDonnell Range and the country to the east, obtained at the first 
locality a single abraded example of Angasella setigera^ and at the latter several 
live specimens of Thersites perinfiata. 
Since the return of the Expedition there has appeared a description of Hadra 
adcockiana. This species was abundantly collected by me, and proved to be very 
variable in shape, sculpture and colouration ; whilst the few specimens communi¬ 
cated by Mr. Thornton, late of Tempo Downs, to the author of the species belong 
to a somewhat rare and extreme variation. 
Because of the risk of being anticipated in the authorship of other species 
collected by the Expedition, arising from the consideralile lapse of time before 
publication in this volume, I communicated “ Brief Diagnoses ” of the new species 
to the Royal Society of South Australia, which were published in its Transactions, 
1891:. Therein Charopa is used in its restricted sense, and Hadra as the equivalent 
of Thersites. 
The comparisons with defined species are based on authentic specimens, except 
when otherwise stated. All measurements are in millimetres. 
It is much to be regretted that I neglected to preserve the animals as they 
were collected, instead of trusting to the hope that they would survive the journey 
to Adelaide. The larger species did exhibit that amount of endurance, but all the 
smaller ones were hopelessly dessicated. In this way the opportunity has been 
lost of ascertaining the visceral structure of many species, which would have 
furnished a key to their classifactory position. What material has been secured 
has been reported on by Mr. C. Iledley in the accompanying appendix. 
2. xVffinities and Geographic Relationships. 
The number of species of land mollusca now known to inhabit that portion of 
Central Australia which I have named Larapintine (see Botanical Report) is 
twenty-five. Four of them extend beyond the area and five others are near allies 
of extra-limital species. The remaining sixteen oiler such distinctive characters 
that they must be regarded as restrictively endemic. These facts are expressed in 
the following list of species and their exoteric representatives : — 
