146 JOUENAL OF THE NEW JERSEY 



Height to apex 12i^; D. 20. — New Jersey and north. Common. 

 2. Crepidula, Lam. 

 Shell oblong, with an internal plate covering the posterior half. 



1. Crepidula fornicata, L. (Figs. 41, 42). Shell quite convex, 

 with one side more oblique than the other; surface transversely 

 wrinkled ; partition slightly concave, about ^ the size of the ob- 

 long aperture. Generally reddish in color, sometimes spotted, 

 occasionally white. L. 25-40; W. 16-30.— Whole extent. 

 Abundant. 



2. C'repidida convexa, Say. Shell small, opaque, very convex, 

 obliquely-ovate, one side nearly vertical, the other sloping ; sur- 

 face wrinkled ; apex acute, separate from the body of the shell, 

 turning to one side and downward to the tip of the shell ; aper- 

 ture oval; diaphragm deep, convex, less than half of the aper- 

 ture. Color ashen-brown with bands, or spots of reddish-brown. 

 L. 12; W. 8; Height 4. On seaweeds and stones throughout. 



3. Creioidida plana, Say. Shell flat or reversed concave, ovate 

 to quadrilateral in outline ; surface wrinkled. Pure white. L. 

 28-50; W. 15-30.— Whole extent. Usually within shells. 



Family 67. NATIClDyE. 



Shell globular or Oval; spire usually short; aperture semi- 

 lunar, without canal or notch; outer lip sharp; columella lip 

 callous, more or less reflected over the umbilicus. 



Animal with small tentacles which are lanceolate, wide apart, 

 united by a veil ; eyes absent or minute ; mantle enclosed ; foot 

 much produced in front, where it is furnished with a fold which 

 covers the head and tentacles ; operculum paucispiral, corneous. 

 Marine. Eggs deposited in a curious, sand formed ribbon which 

 is bent in a circular form, constricted into a neck above. 



* Aperture less than half the area of the shell 1. Natiea. 



* Shell ear-shaped; aperture over half the area 2. Sigaretus. 



1. Natica, Lam. 

 Shell sub-globular, spire slightly elevated; aperture half round- 

 a spiral callus on the pillar, entering more or less into the umbili- 

 cus. Animal blind, completely retractile within its shell ; oper- 

 culum with an external, limy layer. 



* Shell over 20 long. (A.) 



A. Umbilicus widely open ^. 3. 



