1855.] 261 



MITRA. 



Subgenus Fusimitka, Conrad. 



Elongate-fusiform, smooth and polished with impressed revolving lines ; aper- 

 ture narrow ; plaits two prominent, and two obsolete, or much smaller than the 

 others; beak elongated. 



To this subgenus belongs M. conquisita, Con., M. Mississippiensis, and 

 Con., of the Vicksburg deposit. 



M. (Fusimitru) Mellivgtoni, PI. xvi. fig. 5. Profoundly elongated, fusiform; 

 volutions ten, convex, six of which towards the apex have revolving impressed 

 lines, with the interstices transversely striated; in the contiguous whorl they are 

 distant and obsolete, except near the summit, where there are two distinct im- 

 pressed lines ; on the penultimate whorl one distinct impressed line, and the 

 summit of the body whorl obtusely carinated; spire longer than the aperture, 

 which is narrow ; plaits four, the two superior ones very prominent, robust. 



Allied to M. conquisita s but much larger, proportionally longer, and with 

 the striae less deeply impressed. It may prove, however, to'be the same when 

 many specimens from the two localities can be compared. If it should be iden- 

 tical with the former it is the only species common to the Vicksburg and Jackson 

 deposits out of 40 species of the latter and 100 of the former deposit. 



CARICELLA, Con. 



1. C subangulata, PI. xv. fig. 8. Turbinate; labrum expanded ; shoulder 

 subangulated ; body whorl flattened above ; spire short, conical, consisting of 

 4 volutions, with microscopic revolving lines near the apex ; columella with 

 four remote plaits, the two inferior ones most oblique. 



2. C.polita, PI. xvi. fig. 4. Fusiform; smooth and polished, with revolving 

 lines inferiorly, and on two volutions of the spire ; the whorl above is papillary 

 and smooth ; columella with closely arranged microscopic longitudinal lines ; 

 plaits four, slender, prominent, remote ; beak slightly curved. 



Allied to C. but proportionally shorter and very distinct. 



SCALARIA, Lam. 



S. nassula, Con., PI. xvi. fig. 6. Foss. Shells of Tert. Form. 

 This shell, though much larger than the Claiborne specimens, specifically agrees 

 with them. Probably Lea's S. plamdata is the same species. 



ARCHITECTONICA, Bolton. SOLARIUM, Lam. 



1. A. acuta, PL xvii. fig. 1. Much depressed, very thin and acutely cari- 

 nated on the margin; convex above, lower half of the whorls somewhat exca- 

 vated ; revolving striae linear, crenulated, with a minute intermediate crenulated 

 line, and a still finer line or two in some of the interstices ; base convex, flattened 

 and somewhat excavated towards the periphery, revolving striae linear, alternated 

 with a medial smaller line and two minute ones, nearly smooth, except four 

 from the umbilical margin, which rapidly increase in size towards the inner 

 margin; the marginal line profoundly crenulated ; a carinated beaded line on the 

 middle of each whorl within the umbilicus, which is profoundly scalariform. 



2. A. bellastriata, PI. xvii. fig. 2. Discoida], with radiating impressed lines, 

 which frequently bifurcate and are most profound at the suture ; whorls of the 

 spire carinated below near the suture ; periphery acutely carinated, margined 

 above by two approximate raised lines, and below by a prominent line which is 

 slightly marked by a microscopic impressed line ; base with three impressed 

 lines, that nearest the umbilicus profound; radiating striae interrupted by the 

 revolving lines ; base convex towards the periphery and concave towards the 

 umbilicus. 



