NUCULIDA, DAY 
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 by their apposition a third siphon. 
ADRANA, H. and A. Adams, 1858. Shell thin, gaping at the 
extremities. L. Sowerbyana, d’Orb. (exxvi, 32). 
NEILONELLA, Dall, 1881. Shell not gaping, epidermis polished, 
ligament central. LZ. corpulenta, 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? JL. protexta, Con. Cretaceous; New Jersey. 
Youpra, Moller, 1832. 
EHtym.—Dedicated to the Countess Yoldi. 
Distr.—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 (exxvii, 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. Valves posteriorly closed. 
_ PHASELOTUS, Jeffreys. Like Yoldia, but teeth less numerous, 
moderately long, oblique, in two diverging rows. Recent and 
Pliocene. 
Materia, Desmoulins, 1832. 
Syn.—Solenella, Sowb., 1832. Ctenoconcha, Gray, 1840. 
Distr.—2 sp. Valparaiso; New Zealand. JM. Chilensis, Desm. 
(exxvi, 34. Fossil sp. Miocene; Point Desire, Patyeonia ; 
Italy. 
Shell oval, compressed, smooth 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. 
1g; 
