310 MAZATtAN UNIVALYES 



Tablet 1499 contains 6 sp. broken so as to shew the internal 

 laminae. 1500, a mass almost covering Murex princess, with a 

 F Sphaenia in a varical foliation. 1501, Uvanilla olivacea, with 

 several specimens attached. 1502, 2 sp. of U. nnguis, do. 

 1503, Leucozonia cingulata, do. 1504, 3 sp. Cuma costata, do. : 

 in one, the P. macrophragma has been removed, shewing the 

 amount of erosion. 1505, Rhizocheilus nux, Pisania gemmata, 

 and Coluinbella fusca, do. 1506, Omphalius ligulatus and 

 Fissurella rugosa, do. 



Opercula of Vermetidce. 



(a.) Operculum o. "Alette centig/uadrce" simile, sed magis 

 regulariter multispirale ; extus parum concavum, marginibus 

 anfractuum Icevibus, parum extantibus, umbone centrali elevatd; 

 superficie anfr. circiter viii., uvibone iv. instructis ; intus cica- 

 trice magnd irregulariter concentrice rugosa. 



Tablet 1507 contains one of three opercula, probably belong- 

 ing to a second species of Aletes. 



(b.j Operculum spirale, corneum, subolivaceum, tenue ; extus 

 parum concavum, marginibus valde tenuibus, haud regularibus ; 

 anfr. circiter [xv. haud distincte definitis, haud extantibus, ad 

 apicem haud umbonatum ascendentibus ; intus cicatrice parvo, 

 vix corrugato. 



Tablet 1508 contains two opercula, which probably belong^ 

 to an Aletes. 



(c.) Operculum haudparvum*, haud regular e, corneum, tenue, 

 diaphanum ; extus subconcavum, laminis parum elevatis, urn- 

 bone extante : intus vix convexum, liris ? concentricis multis 

 subdistantibus, subextantibus, margine parvo; cicatrice parvd, 

 irregulariter concentrice rugosa. 



Tablet 1509 contains an operculum, in poor condition, inter- 

 mediate between Aletes and Yermetus proper; remarkable 

 for the internal ridges, which are not. crowded into the middle 

 portion, and leave a comparatively small margii*. 



(d.) Operculum distincte spirale, tenue, corneum, diaphanum ; 

 extus marginibus parum convexis ; lamina concavd solutd, l&vi, 

 acutd, spirahter ascendente, anfr. internis conveniente, apice 

 parum elevato, vix umbonato : intus parum convexnm, triente 

 internd anfr. multis ; trientibus duabus externis anfractu ultimo 

 occupalis ; cicatrice vix corrugatd. 



