440 MARINE INVERTEBRATES 
Genus Cardita 
C. borealis. A very common species north of Cape Ann, reported 
also in deeper water as far south as Hatteras. It is a solid, obliquely 
heart-shaped shell, with beaks elevated and turned forward. It has. 
about eighteen to twenty rounded radiating ribs, 
which are broader than the grooves between 
them. Theepidermisisrusty-brown. The hinge 
‘is strong, with two prominent teeth; the mar- 
gins of the shell are strongly crenulated within. 
Length one inch; height about the same. This 
is not strictly a between-the-tides species, but 
its valves are often cast upon the beaches. Fine 
specimens may be obtained by dredging at Bar 
Harbor or Eastport. 
C. floridana. <A very common Floridian 
species. Its seventeen or eighteen ribs are very 
heavy, and are rendered nodulous by the numer- 
ous bluntly raised scales upon them. The shell is lengthened, and has a 
well-defined lunule and an external ligament. In color it is yellowish- 
white, with purple markings when young. Length one inch; height three 
fourths of an inch. It lives in sheltered bays; detached valves are 
often found cast upon the beach. 
Cardita borealis, natural size. 
FAMILY ASTARTIDE 
Genus Astarte 
Notwithstanding their rather small size, there is a trimness 
about the shells of Asfarte which, taken together with their 
rich chestnut epidermis, makes them very interesting and desira- 
ble additions to the cabinet. The family is one of cold-water 
range, with a few representatives on the New England coast. 
Live specimens are not easily captured, for they live in deeper 
water than one would care to wade in, nevertheless they are fre- 
quently cast upon the beaches after storms. The animal has a 
very short efferent siphon, large labial palps, and very obliquely 
placed gills. Not more than twenty living species of Astarte are 
known, and all of them belong in, or are wanderers from, polar 
seas. Fully three hundred fossil species of this genus have been 
described from Mesozoic rocks in all parts of the world. The 
question naturally arises whether in these its dying days Astarte 
has sought colder waters in which to pass its remaining existence, 
or whether climates have changed. The fact that such strictly 
