290 [Oct. 1847. 



toma ; spire long, turreted ; pillar lip wanting ; columella with plaits decreas- 

 ing in size downwards, as in Mitra ; canal short. 



Scobinella cozlata. 



Subfusiforrn ; volutions eleven, slightly scalariform, with longitudinal ir- 

 regular ribs and revolving impressed lines ; ribs interrupted on the spire by a 

 tuberculated convex space ; suture margined by a row of fine tubercles or 

 grains ; labium with four, rarely five plates. Length 1 3-10. 



This singular shell is perhaps more nearly related to Pleurotoma than to 

 Mitra. The plates in most specimens resemble those of the latter genus, but 

 in one instance where there are five plaits, the middle is the largest and 

 thickest, the lowest one being minute. 



1. Turbinella Wilsoni. 



Fusiform ; spire elevated, acute, volutions ten, angular, nodose, the larger 

 volutions somewhat concave above ; the upper volutions with revolving lines, 

 obsolete or wanting on the lower ones ; beak with coarse, slightly raised revol- 

 ving lines ; aperture narrow ; columella with three rather distant compressed 

 plaits, the middle one largest ; canal long. Length 5 inches. 



The young of this species has distinct lines on every part of the shell, ex- 

 cept on the large portion of the body whorl, where they are indistinct and re- 

 mote. This species is named to commemorate the scientific zeal of Dr. Thomas 

 B. "Wilson. It is rare, and generally very imperfect. 



2. Turbinella protracta. 



Fusiform, with about nine volutions, with thick, prominent, longitudinal 

 ridges, and revolving, thick, prominent lines, with a fine intervening line ; 

 longitudinal wrinkles distinct ; whorls concave above ; spire elevated, acute ; 

 columella with four plaits, the lower one dentiform ; canal long ; labrum striated 

 within. Length 1 5-10. 



3. Turbinella perexilis. 



Narrow-fusiform, with convex volutions, having large, rounded, longitudi- 

 nal ribs, about six on the large whorl ; revolving lines strong, prominent, dis- 

 tant, with a fine intermediate line ; longitudinal wrinkles minute and orna- 

 mental ; aperture narrow ; labrum striated within: columella with two larg^ 

 plaits; beak long and narrow. Length 1. 



Distinguished from the preceding by its narrower outline, fewer and larger 

 plaits on the pillar, &c. It is probably a much smaller species, but as I have 

 one specimen only, its greatest size cannot be determined. 



Panopcea oblongata. 



Elongated, very inequilateral, ventricose ; extremities rounded : umbo promi- 

 nent, undulated ; valves slightly contracted at base in a line with the urn- 

 bones : valves gaping at both ends. Length 3J. 



Occurs in its original vertical position generally with connected valves, but 

 it is extremely friable and difficult to obtain. 



1. Mactra 3fississippiensis. 



Subtriangular, equilateral, very thin and fragile, plano-convex, dorsal margin 



