NO. 1237. SYNOPSIS OF THE LUCINACEA—DALL. 815 



Subgenus Lucinella Monterosato, 1883. 



Shell like iJiniricella, but the ligament obsolete and the resilium 

 wholl}^ internal, as in Semele. Type, Lucina commntata Philippi, 

 1836, = Telliim dlvarlcata Linnteus, 1758; Mediterranean and western 

 Europe. 



LIST OF THE AMERICAN SPECIES. 



DIVARICELLA QUADRISULCATA d'Orbigny, 1846. 



Nahant Beach, near Boston, Massachusetts, and southward to the 

 West Indies, Rio de Janeiro and Santa Caterina, Brazil, in from li) to 

 50 fathoms. 



This is (from types) Lucina strlgUla Stimpson. 1851, and L. divari- 

 cata of Gould, 1811, and other earl}^ writers. It is also the Lucina 

 amerlcanaoi C. B. Adams in 1852; the Oyclas dentataoi Verrill, 18T3, 

 and the Lucina commutata Araugo, 1878, not of Philippi, 1836. A 

 variety transve7\sa Dall, 1901, with the valves disproportionately elon- 

 gate in the direction of the hinge line, has been dredged in 22 fathoms 

 off Cape Lookout, North Carolina, by the U. S. Fish Commission. 



This species is distinguishable from the next hj its longer, small and 

 narrow, somewhat sinuous lunule and fine crenulation of the interior 

 margins. The adult has no denticulations of the outer margin due to 

 the external sculpture. 



DIVARICELLA DENTATA Wood, 1815. 



Cape Hatteras, North Carolina, south to the West Indies (and, 

 according to d'Orbigny, to Brazil), in 10 to 60 fathoms. 



It is the Lucina, divaricata of many of the early writers, but not of 

 Linnffius; but not the Lucina dentata of Def ranee, 1823; the Z. ser- 

 nita of d'Orbigny, 1846; the L. chem/)ntzii of Philippi, 1818, and the 

 L. pilula C. B. Adams, 1852 (young shells), are synonymous. 



It may be known by its very small, deep, cordate lunule at any age, 

 and in the adult it differs from D. quadrisulcata, by its greater size and 

 the denticulation of the lateral and dorsal margins by the external 

 sculpture. The large specimens have a tendency to obsolescence 

 noticeable in the teeth, and the laterals are often quite imperceptible. 



DIVARICELLA EBURNEA Reeve, 1850. 



Cape St. Lticas, Lower California, and southward to Panama. 



It is the Lucina ehurnea of Reeve, 1850, but not of Deshayes, 1835. 

 It may be distinguished from the Antillean D. quadrimdcata d'Orbigny 

 by its shorter, wider, and cordate lunule, and by the well-developed 

 lateral teeth, which are well marked and distinct at all ages. The 

 sculpture is also usually more arcuate. 



DIVARICELLA PERPARVULA Dall, 1901. 



Cape St. Lucas, Lower California, south to (Tuacomayo. 



This is the Lucina ijisitni of Philippi in April, 1850, but not of 



