NUCULID^. ^49^ 



Animal furnished with two partially united, slender, unequal, 

 siphonal tubes; gills narrow, plume-like, deeply- laminated, 

 attached throughout ; mantle-margin with small ventral lobes 

 forming b}^ their apposition a third siphon. 



ADRANA, H. and A. Adams, 1858. Shell thin, gaping at the 

 extremities. L. Sowerbyana^ d'Orb. (cxxvi, 32). 



NEiLONELLA, Dall, 1881. Shell not gaping, epidermis polished, 

 ligament central. L. corpuleata, Dall. Havana. 



PERRISONOTA, Conrad, 1869. Shell elongated, posterior hinge- 

 line long, curved, linear, with numerous close transverse teeth, 

 extending nearly to the end margin ; anterior hinge-area broad, 

 oblique, and somewhat distant from the hinge margin ; no fosset 

 under the apex ? L. protexta^ Con. Cretaceous ; New Jersey. 



YoLDiA, Moller, 1832. 



Etym. — Dedicated to the Countess Yoldi. 



Bistr. — -Arctic and Antarctic seas, Greenland, Massachusetts 

 Brazil, Norway, Kamtschatka. Yoldia limatula has been dredged 

 alive, by Mr. M'Andrew, on the coast of Finmark. It is also 

 found in Portland Harbor, Maine. Fossil; Silur. — . Y. myalis, 

 Couth, (cxxvi, 33). 



Shell oblong, slightly attenuated behind, compressed, gaping, 

 smooth or obliquely sculptured, with dark olive shining epider- 

 mis; external ligament slight; cartilage as in Leda; pallial 

 sinus deep. 



Animal (cxxvii, 61) with the branchial and anal siphons united, 

 retractile; palpi very large, appendiculate ; gills narrow, pos- 

 terior ; foot slightly heeled, deeply grooved, its margins crenu- 

 lated ; intestine lying partly close to the right side of the body, 

 and producing an impression in the shell ; mantle-margin plain 

 in front, fringed behind ; destitute of ventral lobes. The animal 

 •is very active, and leaps to an astonishing height, exceeding in 

 this faculty the scollop-shells. 

 - PORTLANDIA, Morch. Yalves posteriori}^ closed. 



PHASELOTUS, Jeffi'ej^s. Like Yoldia, but teeth less numerous, 

 moderately long, oblique, in two diverging rows. Recent and 

 Pliocene. 



Malletia, Desmoulins, 1832, 



^y,j._Solenella, Sowb., 1832. Ctenoconcha, Gray, 1840. 



Distr. — 2 sp. Valparaiso; New Zealand. 31. Ghilensis,'Desw. 

 (cxxvi, 34\ Fossil sp. Miocene; Point Desire, Patagonia; 

 Italy. 



Shell oval, compressed, smootli or concentrically furrowed,, 

 epidermis olive; ligament external, elongated, prominent; hinge 

 with an anterior and posterior series of fine sharp teeth; interior 

 subnacreous ; pallial sinus large and deep ; anterior adductor 

 giving off a long oblique pedal line. ' ' ■ . 



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