PELECYPODS 445 



margin is striking. It has very fine cardinal teeth. Length two to 

 three inches. 



M. baltica, M. proxima, M. tcnta. The first two of these species 

 are dingy in color, and are covered with a dirty-looking, thin epidermis. 

 The first has a wide range to Norway and Scotland, and is exceedingly 

 common all along our coast from Maine to Georgia. 

 It occurs plentifully in the Hudson River above 

 New York, and in all sandy or muddy bays. It is 

 rounded in outline, while the next species (M. 

 proxima) is more pointed posteriorly. When these 

 species are buried in the sand their two long, slen- 

 der siphons project above, one supplying the animal 

 with a constant current of fresh water, and the other 

 ejecting that which, having passed the gills and Macoma i>itica. 

 labial palps, is exhausted of its air and nutriment 

 and contaminated by waste products. M. tenta is 

 white, with very fine lines of growth, and polished 

 and shining within. It is warped posteriorly. Length 

 three fifths of an inch ; height two fifths of an inch. 



FAMILY DONACID.E 

 GENUS Donax 



The Donacidce are represented upon our coasts by compara- 

 tively few species, all belonging to the genus Donax. The shells 

 are under an inch in length, and have a peculiarly shortened an- 

 terior portion ; thus they are inequilateral. Their ventral mar- 

 gins are finely denticulate. The pallial sinus is deep. There are 

 two or three cardinal teeth and a variable number of laterals. 



D. variabilis. This little shell, the common Floridian form, exhibits 

 every imaginable scheme of color-combination, and defies general or 

 comprehensive description. Probably the most usual pattern developed 

 is a bluish-white background with purplish radiating lines. Another 

 is a pure- white foundation with red lines. The surface is striated longi- 

 tudinally with excessively fine riblets. Length one half of an inch or 

 slightly more. In March and April these shells are thrown alive in 

 millions upon the Florida beaches. Each wave seems to be laden with 

 them, and when the foaming waters of each spent breaker recede, the 

 little shells lie still upon the sand for a moment, glittering like jewels in 

 the sunlight ; then, with a sudden protrusion of the foot and a quick 

 turn, they all disappear like a flash, buried in the sand before the next 

 breaker strikes them. One must be very quick to catch these active lit- 

 tle mollusks. (Plate LXXXI.) 



1). californicus. Professor Keep very aptly describes this shell, 

 which is very common in California, as " short and stumpy, cut 

 nearly square off at one end (anterior), and tapering to a rounded edge 

 at the other." The same description fits both this and the Floridian D. 

 variabilis so well that the two forms may be one and the same species. 



