454 MARINE INVERTEBRATES 
purple lines or spots; the brownish-purple posterior area—all combine 
to make this large Cardium a beautiful species. Its length is four inches; 
height five and a quarter inches. It is a very abundant species on the 
open Florida beaches, where it is often left exposed and alive at very 
low tides. (Plate LXXXIV.) 
C. isocardia.. This also is a Floridian species, of elongated heart- 
shape and with radiating ribs, It is not more than half as large as the 
last-described species. The ribs are decorated with erect vaulting scales 
which are exaggerated portions of growth-lines, The beaks are smaller 
in proportion than in C. magnum. The shell is brown to straw-color, 
stained with purplish-brown without, and has a bright salmon-red or 
purplish-pink interior. The margins are deeply crenulated. The teeth 
are arranged as in the last-described species. It is very common on the 
beaches of western Florida. (Plate LXXXIV.) 
C. serratum, C. levigatum. These two species have a perfectly 
smooth surface, and inflated, globose, heart-shaped shells, and are of a 
creamy-white color, suffused with a yellowish, golden tint which suggests 
the color of butter. Some forms are shiny, and citron-yellow and pinkish 
toward the margins, whence the name of ‘‘ peach-shell.” Height one to 
two inches. Not uncommon upon Florida beaches. (Plate LXXXIV.) 
C. mortoni. Another of the smooth forms of Cardium (placed in the 
subgenus Levicardium). It oceurs in Florida and also extends up the 
coast to Cape Cod, being very abundant in Long Island Sound. In 
the neighborhood of Martha’s Vineyard and along 
the north shore of Long Island this very pretty 
little species has been reported as occurring in soft 
ground even above low-tide mark, near the mouths 
of creeks. It is enough to say of it that it is a 
smaller edition of C. levigatum and may be further 
distinguished by a purple blotch on the posterior 
margin, just within the valves, the general color 
within being bright yellow. In young specimens, 
Cardium mortom, showing zigzag lines of dark fawn-color upon the pale- 
oxvondedanitasl: yellowish background of the smooth exterior sur- 
face of the shells are a noticeable feature. The largest specimens mea- 
sure an inch in length and nearly the same in height. The long cirri 
upon the siphons are striking. 
C. substriatum. A cockle of this inflated, smooth type, which 
strongly resembles the east-coast form, found upon the Pacific coast. 
The name indicates that it is not altogether smooth, a fact only revealed, 
however, by a magnifying-glass. It is about one half of an inch in 
length, and of a light drab-color, spotted and sometimes radially lined 
with yellowish-brown. Professor Keep likens this species in both shape 
and color to a sparrow’s egg. (Plate LXXXIV.) 
C.elatum. A veritable giant among the cardiums. It is found on 
the southern Californian coast, though rarely north of the Mexican 
border. It is of the smooth, glossy type belonging to the subgenus 
Levicardium. It attains a diameter of ‘six inches, and is of a creamy- 
yellow appearance. 
C. corbis, C. quadrigenarium. These two Californian cockles are 
of the ribbed type displayed in the eastern C. magnum and. C. isocardia. 
C. corbis is found in the northern Californian and Puget Sound region, 
