106 



MR. LOVEL.L REEVE ON A NEW PHYSA. [Mar. 11, 



convex and typically smooth ; but there are two (Z. ovata and emai'- 

 ginata, Say) which incline to develop obscure, irregularly formed 

 ridges. The ridges of these Limncece 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. 



Physa (Ameria) alici^. Ph. testa anguste obtecte umbili- 

 cata, suboblongo-ovata, tenui, inflata, fiavescenti-cornea, spira 

 parviuscula plus minus acute exserta ; anfractibus tribus ad 

 quatuor, superne subabrupte declivi-angulatis, deinde converts, 

 transversim undique Jiloso-liratis, liris incequalibus incequidi- 

 stantibus, interstitiis striis fibrosis incrementi, super liras et ad 

 suturas plicato-scabrosis, creberrime longitudinaliter decussa- 

 tis; apertura suboblongo-ovata, labro tenuissime membranaceo 

 refiexo. 

 Long. |, lat. I 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 {Angas). 



"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 inflated 

 oblong structure, with a rather small spire, sharply esserted, 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 striae of growth cross the interstices between the ridges in very 

 close and strongly marked succession, and in the sutures and on 



