214 HORX EXPEDITION—MOLLUSCA. 
1873.— Physa latilabiatd, Sowerby. 
1873.— Physa siibiri/lata, Sowerby. 
1883.— Physa brazieri, Smith. 
1883.— Physa schayeri, Troschel. 
1888.— Limncca physopsis, Cooke. 
The species known to me are 1. newcombi^ /. iiiflata^ and /. brazieri, and it is 
a grave question with me whetlier or not they are but moditications of one species. 
Linimca physopsis is too much like /. infiata or the sliort-spired forms of 
I. newco/nbi to merit varietal distinction. Physa subinflata would seem to be from 
the figure an elongate individual of /. newcombi ; the figure shows, however, a 
slight twist on the columella, but this may be an error, as in the case of Reeves’ 
figure of I. newcombi ; at any rate I am unacquainted with any other South 
Australian shell of the family to which the figure and description of Physa sub¬ 
inflata is applicable. P. latilabiata is regarded by Smith as synonymous with 
P. hainesii, and P. schayeri also belongs there. By these reductions the genus 
comprises three species— I. newcombi, with its two varieties, inflata and brazieri, 
/. hainesii, and /. ferruginea. Paetel, Cat. Conch., vol. ii., p. 410, 1889, includes 
Physa aperta. Sow., in the genus Isidora, which is the only Australian species of the 
genus admitted by him; this is a grave error, and at variance with the original 
diagnosis, “ columella tortuous, fold rather prominent,” and with the figure. 
/. neivcombi and its varieties have the test covered by a horny periostracum 
raised into spiral fringes of hairs and into imbricating folds at the suture; the 
spiral rows of hairs are superimposed on the spiral striie of the test; the peri¬ 
ostracum is more developed in some individuals than in others, may be partly or 
wholly removed by abrasion in adult shells, and is usually lost in dead ones. This 
feature has been unnoticed by the describers of the several species, which may be 
explained on the probability that their types were dead shells. The colour of the 
test is mainly light-horn, but varies from olive-green to brown and reddish, and 
cannot be used as a specific character. 
I. newcombi and its varieties have the habit of burrowing in the mud on the 
drying up of the water of the pool in which they live, and of forming a hemi¬ 
spheric operculum of fine silt, thus closing the aperture. The fine nature of the 
material forming the operculum contrasts strongly with the varied texture of the 
mud of the pool, which leads me to infer that the fine sediment has been selected 
by swallowing and ejected per anum. The associated species of Bulinus may 
secrete themselves under stones or logs, but the majority are left high and dry by 
the receding water. 
