1861.] MR. H. ADAMS ON NEW SHELLS. 385 



Shell elongate, thin, radiately plicate, the plicae and the interstices 

 striated, covered with a pale-brown epidermis ; spire elevated, the 

 apex eroded, the sutures distinct ; whorls 7, rather convex, furnished 

 with thin ribs at the sutures, the last less than half the length of the 

 shell, and sulcated at the base; aperture oblongo-ovate, white within ; 

 columella smooth, rather callous. 



Genus Cryptoplax, Blainville. 

 Subgenus Notoplax, H. Adams. 



ValvcB fere cequales, acuminatim cordatee, disjunctce, interstitiis 

 mediocribus subcequalibus ; area lateralis subconspicua. 



Valves of nearly equal size, acutely cordate, disunited, the intervals 

 between them moderate and nearly equal ; lateral area slightly in- 

 dicated. 



Cryptoplax (Notoplax) speciosa, H. Adams. 

 C. testa elongata ; valvis acuminatim cordatis, olivaceis fusco 

 maculatis, utraque lata, lavi, costa in dorso instrueta, margi- 

 nibus crasse granosis, area laterali elevata linea indicata. 

 Limbusfuscus, spinulosus; poris mediocribus, spiculis conspicuis 

 cinctis. 

 Long. 36 ; lat. 12 lin. 

 Hab. Tasmania. 



Shell elongate ; valves acutely cordate, olivaceous with brown 

 markings, each with a broad smooth dorsal ridge, the sides coarsely 

 granular, the lateral area indicated by a raised line. Mantle brown, 

 spinulose ; the pores moderate, surrounded by conspicuous spicula. 

 This species is interesting from its possessing characters peculiar 

 to both the genera Cryptoplax and AcanthochcBtes. The separation 

 of the valves, however, induces me to place it in the former, but with 

 the rank of a subgenus. 



Genus Semele, Schumacher. 



Semele exigua, H. Adams. 



<S. testa oblonga, transversa, incequilaterali, nitida, tenui, alba, 

 concentrice tenuissime striata ; latere antico longiore, rotundato, 

 postico breviore, subangulato, ad marginem ventralem valde 

 fiexuoso ; intus alba. 

 Long. 6| ; lat. h\ lin. 

 Hab. Tasmania. 



Shell oblong, transveise, inequilateral, shining, thin, white, finely 

 striated concentrically ; anterior side the longer, rounded ; posterior 

 side the shorter, subangulated, with a strong fold continued to the 

 ventral margin ; white within. 



Proc. Zool. Soc— 1861, No. XXV, 



