APPENDIX TO PART I. 



DESCRIPTION OF FOSSIL SHELLS. 

 By G. B. SOWEEBT, Esq., F.L.S. 



Shells from a Tertiary deposit, beneath a great basaltic 

 stream, at St. Jago in the Cape de Yerde Archipelago, 

 referred to at p. 6 of this volume. 



1. Lixtoeina plai^axis. G. Sowerby. 



Testa subovatd, crassd, Icevigatd, anfractibus quatuor, spiraliter 

 striatic; aperturd subovatd ; labio columellari infimdque parte 

 anfr actus ultimi planatis : long. 0*6, lat. 0*45, poll. 



In stature and nearly in form this resembles a small periwinkle ; 

 it differs, however, very materially in having the lower part of the 

 last volution, and the coluinellarlip as it were cut off and flattened, 

 as in the Purpurse. Among the recent shells from the same locality, 

 is one which greatly resembles this, and which may be identical, but 

 which is a very young shell, and cannot therefore be strictly com- 

 pared. 



2. Ceeithitjm jemtjlum. O. Soiverby. 



Testa oblongo-turritd, subventricosd, apice subulato, anfractibus 

 decern leviter spiraliter striatis, primis serie unicd tuberculorum 

 instructis, intermediis irregulariter obsolete tuber culifer is, ultimo 

 longe majori absque tuberculis, sulcis duobus fere basalibus in- 

 structo ; labii externi margineinterno intiis crenulato : long. 1*8, 

 lat. 07, poll. 



This species resembles so nearly one of the shells brought to- 

 gether by Lamarck, under the name of Cerithium Vertagns, that at 



