1818.] OF THE UNITED STATES. 385 



filiform, inner tip of the antipenultimate joint dilated into 

 a compressed, accessory tubercle at the inner tip, penul- 

 timate joint dilated and rounded at the inner tip for the 

 reception of the nail; hands of the second pair of feet 

 dilated, oval, palm elevated in the middle into a large 

 rounded tooth, which touches the middle of the thumb 

 when at rest, leaving an interval on each side, an elevated 

 ©btuse angle at the tip of the palm, on the inner side of 

 which the thumb rests when closed, lower edge of the 

 hand rather longer than the palm. 



Female with the second pair of feet simple, compres- 

 sed, destitute of hair or short bristles, and unarmed with 

 a nailj terminal joint of the antennae twenty-eight to thir- 

 ty articulate. 



Length seven tenths, breadth one fifths of an inch. 



The manners and habits of the animals of this genus 

 are similar; they do not inhabit the waters, but are found 

 in considerable numbers upon sandy beaches of the sea, 

 and are well known to every observer by the name of 

 sand fiea; they leap about with great agility, feed upon 

 and conceal themselves under the rejectamenta of the sea, 

 and for repose and security dig a hole in the sand, to 

 which they skip at the approach of danger; they furnish 

 an excellent food for the shore birds, which may be seen 

 constantly running about in pursuit of them. The young 

 males of this species have the antennas not longer than 

 the females, but the number of articulations is not dimi- 

 nished. Colour in the dried specimen brownish. The 

 longicornis differs in some of its characters from the ge- 

 nus Talitrus as defined by Dr. Leach, particularly in the 

 form of ihe two anterior pairs of feet, which approximate 

 it to Orchestia. 



