250 NUCULID. 
Animal like Yoldia; mantle-margins slightly fringed and 
furnished with ventral lobes; siphonal tubes united, long, and 
slender, completely retractile ; palpi appendiculated, convoluted, 
as long as the shell; gills narrow, posterior; foot deeply cleft ; 
forming an oval disk, even-margined and striated across. 
NEILO, H. and A. Adams, 1855. Shell transverse, gaping, sub- 
truncated, rostrated behind; surface concentrically striated ; not 
nacreous within; cardinal hinge-line nearly straight. IM. Cum- 
angit, A. Adams (exxvi, 35). Recent. M. Monterosati, Bell. 
Miocene; Italy. 
TINDARTA, Bellardi, 1875. Shell thick, globose, oval, closed, 
beaks swollen; anterior teeth stronger, but the posterior row 
longer. MM. arata, Bell. Pliocene; Asti, Italy. 
NUCULARIA, Conrad, 1869. Shell thin, not pearly, ovately 
elongated, inequilateral, smooth; beaks pointed, subanterior ; 
teeth angular, those of the posterior line complicated. MM. papyria, 
Conrad (exxvi, 36). Cretaceous; Haddonfield, N. J. 
PurnoniA, Hall, 1869. 
Distr.—2 sp. Fossil; Hamilton Group, N. Y. P. sectifrons, 
Conrad (cxx, 8). 
Shell thin, compressed, equivalve, transversely elongate-ovate, 
widening posteriorly and having small obscure subanterior beaks 
‘and an obscure angular umbonal ridge ; surface covered by more 
or less distinct radiating strize or coste, which are crossed and 
eancellated by finer concentric lines, often forming ruge or node- 
like markings on the rays; hinge apparently destitute of teeth ; 
external ligament small, elongated ; adductors small, superficial, 
pallial line apparently entire. 
PALZONEILO, Hall, 1870. 
Distr.—15 sp. Paleozoic; U. 8. P. constricta, Conr. P: 
Bedfordensis, Meek (cxxv, 25). 
Shell Nuculiform, transversely ovate or subelliptical, the pos- 
‘terior end extended, often subrostrate, with a more or less 
defined sulcus along the umbonal slope; concentrically striated or 
ribbed ; hinge-line more or less arcuate, crenulated throughout, 
not interrupted beneath the beak by a ligamental pit, but having 
‘an external ligament; muscular scars distant, faintly marked ; 
‘several small pedal scars within the umbonal cavity ; pallial line 
simple or obliquely truncate posteriorly. 
Differs from Nucula in the want of a ligamental pit, in the 
teeth being continuous under the beaks, in having an external 
ligament, and in the sulcus on the posterior slope. 
Nucuuires, Conrad, 1841. 
Syn.—Cucullella, M’Coy, 1851. Cleidophorus, Hall, 1847. 
