P L A C U N A. 



Species 2. (Fig. a. h, c, Mus. Biit.) 



Placl'na papyracea. Pl(t. testd .semipelliicidd, compressd, 

 purpurea radiatd, subauriculatd, auriculk vix recur- 

 vis, mwgine ventrali leviter recurvo ; valvuld sinintrd 

 mmplanatd ; dentibus laminifonnihus sulxequalibus, 

 subarcuatis ; margine dorsali interdum lobato. 



The papyijaceous Placuna. Shell scmipellucid, com- 

 pressed, rayed with purple, subauriculated, auricles 

 scarcely recurved; ventral margin slightly re- 

 curved, left valve flattened: laminiform teeth 

 nearly equal, a little arched ; dorsal margin some- 

 times lobed. 



Lamauck. Aniniaux sans Vertebres, No. 2. 



Epinppium parvum. Chemnitz. 



Hab. India, Philippines, Australia. 



It is probable that this species was first described 

 from the Indian form, and quite possible that the 

 figures in Chemnitz may have been taken from the 

 young of Placvna sella. Still it does appear th:it there 

 is a species resembling in the young state, but never 

 developing into the adult form of that shell. In tlie 

 Australian examples we have given, two characters are 

 observable which may help to distinguish this species, 

 namely the curved character and smaller divergence of 

 the teeth, and absence of that degree of convexity 

 which distinguishes the lower or left valve of Flacuna 

 sella. Some of the s]iecimens are beautifully raved, 

 and some are much notched or lobed at the dorsal 



November. 187 



