368 MARINE INVERTEBRATES 
inches ; the breadth slightly exceeds the length. P. duplicata has a very 
extensive range, from the Gulf of Mexico to Newfoundland. The 
largest and finest specimens are 
found in the vicinity of New York 
and at Hatteras. In Florida they 
are usually smaller. This species 
cannot be confounded with any 
other upon our coast on account of 
the heavy callous deposit over the 
umbilicus. Its habits are similar 
to those of P. heros. 
Natica clausa. A Northern 
species which is fairly abundant 
on the Maine coast. It 
has a shelly operculum, 
and the umbilicus is @N 
neatly closed by a pure 
white, shining callosity. 
Its length is about one 
half an inch, its color Natica 
lividwhitetolightbrown, “+ 
white within. The calcareous operculum at once determines this shell. 
This species (as well as the following one) has retained the generic 
oe of Natica because of the shelly operculum, as explained 
below. 
N.canrena. One of the handsomer species of Natica, which occurs 
in Florida. Sometimes it is seen as far north as Hatteras. The shell is 
white, with bars of light chestnut circling the whorls, and with zigzag 
lines of darker purplish hue crossing them. The base of the shell is 
white. The aperture is large and flaring, and is purplish within. _ The 
umbilicus is partially closed by an entering callous plug. The operculum 
is calcareous, with eccentric, deeply cut grooves. Found in sandy sta- 
tions just about low-water mark. (Plate LXVIII.) 
P. lewisii. A species which occurs on the west coast of the United 
States. It resembles its New England relative P. heros very closely. P. 
lewisti is a Northern species, and does not range south of Oregon. Pro- 
fessor Keep mentions one specimen of the size of a six-inch globe, but 
such dimensions are very unusual. A good-sized specimen need not 
exceed four inches in height. : 
P. recluziana. A species well known on the southern coast of Cali- 
fornia. The umbilicus is closed by a thick, highly polished white cal- 
losity, and the general shape of the shell is strongly suggestive of the 
common east-coast species P. duplicata. A large specimen is about two 
inches in diameter. 
[There has been much confusion in the generic nomenclature of this 
family. The old name Natica once did service for all the species; then 
the names Lunatia, Neverita, and Polynices were applied to certain spe- 
cial forms; but it has been wisely proposed by conchologists to use the 
name Natica for those forms having a shelly operculum, and to adopt the 
name Polynices for those having a corneous operculum. Lunatia and 
Neverita have become subgenera of Polynices.] 
Polynices duplicata. 
. 
