312 EXPLANATION OF NEW PLATES. 



The same in profile. 



Strophostoma, Desh. three views. 



Fam* Peristomata. 

 Paludina impura. Bithinia, Gray ? 

 Ampullaria avellana. Thallicera, Sw. Ampullarina ? 



539. A species of Ampullaria having a thickened ledge on which 



the shelly operculum rests. Pachystoma, Guild, changed to 

 Pachylabra, Sw. 



Fam. Plicacea. 



540. Ringicula, Desh. A fossil species, front view. 



541. Back view of the same. 



Fam. Turbinacea. 



542. Turbo nicobaricus. Chrysostoma, Sw. 



543. Trochus Iris. Elenchus, Humph. 



Fam, Purpurifera. 



544. Purpura vexilla. Gen. Vexilla, Sw. 



545. Priamus. Achatina priamus, Auct. The propriety of placing 



it in this family will depend upon the correctness of the state- 

 ment made by Dr. Beck that this shell is marine, and pos- 

 sesses an operculum. 



546. Purpura crispata. Polytropa, Sw. 



547. Pseudoliva plumbea. Gastridium, Sow. 



Fam. Canalifera. 



548. Fusus longevus. Clavalithes, Sw. 



549. bulbiformis. Leiostoma, Sw. 



550. Pyrella, Sw. Turbinella Spirillus, Auct. 



551. Pleurotoma lineata. Tomella, Sw. 



552. Pyrula melongena Gen. Myristica, Sw. 



553. Murex vitulinus, Gen. Vitulina, Sw. v 



554. Typhis Sowerbii. 



555. A brown variety of the same. 



556. Typhis Cumingii. 



