Ungulinidae and Lucinidae 63 



Lucinidae. Their distribution is through northern seas almost to 

 tropical waters. 



The shells are equivalve, globose, the umbos prominent, directed 

 forward. The hmge usually has two cardinal teeth in each valve, 

 sometimes but one or none. Ligament internal or partly so. Two 

 elongate muscle scars and simple pallial line. 



Genus TARAS Risso, 1826 



{Diplodotita Brown, 1831) 



Taras punctatus*^ (Say) PI. 11, figs. 63a, b 



Alt., 14; length, 15.5; diam., 10 mm. Shell lucinoid, thin, white, 

 translucent; thin periostracum; umbos prominent, approximate; no 

 lunule; anterior margin slightly concave immediately below umbo; 

 surface of valves smooth, faint concentric striations and microscopic 

 radial striae; two cardinal teeth in left valve, the anterior bifid; two 

 in right valve, the posterior bifid. Interior of valves usually shows 

 opaque, punctate spots most evident near umbonal region. Anterior 

 and posterior muscular impressions; simple pallial line, often with 

 slight irregularities. Pallial lines more removed from shell margin 

 than are outer borders of the muscular impressions. Shell margins 

 smooth. 



Taken in depths of 6 to 125 fathoms. 



Subgenus PHLYCTIDERMAs' Ball, 1899 

 Taras semiasperusss (Philippi) PI. 40, fig. 290 



Alt., 8.5; length, 8; diam., 5.5 mm. Shell small, white, globose; 

 umbos small depressed. Opaque punctations over valve surfaces, 

 on exterior of valves the opaque points are slightly elevated. Other 

 characters correspond to T . punctatus. 



Dredged in six fathoms. 



Family LUt'IJflDAE 



Mollusks of the family Lucinidae are generally distributed in 

 subtropical and tropical seas. Only one genus has accommodated it- 

 self to the rigors of Arctic seas and to great depths. Their normal 

 range is from the littoral region to deep water. The animal has a 



®^ Taras, son of Neptune. Lat., punctus, point. 

 ^'* Gr., phlyktai'va, pustole; derma, skin. 

 ^^ Lat., as per, rough. 



