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; 

 neight 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. Icevigatum. 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 Lcevicardium). It occurs 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. Icevigatum 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, 

 mortoni, showing zigzag lines of dark fawn-color upon the pale- 

 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 

 Lcevicardium. It attains a diameter of six inches, and is of a creamy- 

 yellow appearance. 



C. coring, 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, 



