106 MR. LOVELL REEVE ON A NEW PHYSA. [Mar. 11, 
convex and typically smooth ; but there are two (L. ovata and emar- 
ginata, Say) which incline to develop obscure, irregularly formed 
ridges. The ridges of these Limnee are not, however, analogous to 
the ridges of our new form of Physa. They are not of the same 
symmetrical, persistent growth, and have more the appearance of 
arising from a casual malleation of the surface of the shell. 
Puysa (Ameria) ALic1£. Ph. testa anguste obtecte umbili- 
cata, suboblongo-ovata, tenui, inflata, flavescenti-cornea, spira 
parviuscula plus minus acute exserta; anfractibus tribus ad 
quatuor, superne subabrupte declivi-angulatis, deinde conveais, 
transversim undique filoso-liratis, liris inequalibus inequidi- 
stantibus, interstitiis strits fibrosis incrementi, super liras et ad 
suturas plicato-scabrosis, ereberrime longitudinaliter decussa- 
tis; apertura suboblongo-ovata, labro tenuissime membranaceo 
reflexo. 
Long. 3, lat. 3 poll. 
Hab. Lower Murray River, below Moorandi, and River Gawler, 
South Australia: in small ponds under stones, and attached to aquatic 
plants brought up by the dredge (dagas). 
‘This interesting form of Physa,” writes Mr. Angas, “I should 
like to be dedicated to my eldest daughter Alicia, who found the 
first specimen, and called my attention to it; and I have great 
pleasure in complying with a request so highly deserving of a lasting 
and honourable acknowledgment. ‘The shell is of a slightly mflated 
oblong structure, with a rather small spire, sharply exserted, but 
more so in the specimens from the Gawler than in those from the 
Lower Murray River. Round the upper shoulder, so to speak, the 
whorls are rather narrowly sharply angled, forming a subconcave 
slope from the suture, below which the shell is encircled with thread- 
like ridges. The ridges are parallel throughout, but unequal in 
substance and in distance from each other, being especially finer and 
more crowded towards the base. The outer surface of the shell is 
composed of a yellowish, horny, membranaceous cuticle, of which 
the strize of growth cross the interstices between the ridges in very 
close and strongly marked succession, and in the sutures and on 
