NATURAL SCIENCES OF PHILADELPHIA. 
129 
The uninterrupted series of teeth possessed by the Nuculoid shells already 
referred to, from the Marshall group and its supposed equivalents, seems to 
constitute good grounds for a generic separation. For this hinge structure 
three names have been suggested. Nuculites was assigned by Conrad to shells 
having a continuous series of teeth and an internal clavicular ridge like Cli- 
dophorus. This genus has a real existence in the Hamilton group. Tellinomya 
has been applied by Hall, and Ctenodonta by Salter, to shells having the ge¬ 
neric characters of the species under consideration. As, however, objec¬ 
tions have been urged against the import of the name Tellinomya , and, on the 
other hand, Prof. Hall insists upon the rights of priority over Ctenodonta , (x. 
Report N. Y. Regents, p. 181), it becomes a delicate, matter to decide between 
the two. But since the genus Tellinomya was not founded upon characters 
possessing generic value, while the real generic characters, owing to the state 
of preservation of the specimens, entirely escaped observation ; and, since the 
name proposed actually conveys 3 false idea of the relations of the genus, I 
feel constrained, in spite of my desire to perpetuate an American name, to 
pursue the same course as I do in regard to Athyris and other terms founded 
upon a misapprehension, and, in their meaning, at variance with facts. 
In regard to Ctenodonta Hubbardi, I desire further to admit the possibility 
that this is the species described by Conrad under the name of Nuculites sul- 
catina. All that is stated in the description applies to this species ; and the 
figure also agrees. Nothing, however, is said or shown respecting the hinge 
structure ; and both the description and figure will apply nearly as well to 
Sanguinolites concentrica, Win., which occurs abundantly at the locality 
whence Conrad’s specimens were obtained; while Ctenodonta Hubbardi, so 
far as I have observed, is unknown at that locality. The latter, nevertheless, 
approaches nearest to Nuculites ; and it may be fair to presume that Conrad 
had a view of the hinge structure of the specimens he described. But it must 
be stated, finally, that not one of the hundreds of specimens that I have had 
in my hands, furnishes evidence of the existence of the internal septum which 
is essential to Nuculites and Cucullela. For the present, therefore, I feel 
compelled to regard Nuculites sulcatina, Con., as a species that has not yet 
fallen under my observation. 
Conrad, in the paper referred to, has described Nuculites mactroides. If this 
is really a Nuculoid shell it approaches Ctenodonta sectoralis, Win., without 
being identical. If not a Nuculoid shell, as I suspect,, it approximates Ed- 
mondia cequimarginalis, Win., but at the same time, I could scarcely identify 
it. For the present, therefore, I leave it as I have left the species just refer¬ 
red to. 
Ctenodonta stella, Win. (= Nucula stella, Win.,) also occurs at Napoleon 
Cut, Jackson county, Michigan. 
SANGHJINOLARIA, Lamarck. 
Sangutnolaria rostrata, n. sp. Shell rather large, transverse, cuneate- 
ovate in outline, of medium convexity. Beaks two-fifths the shell length, 
from the anterior end, quite prominent, and rather strongly incurved. Great¬ 
est convexity above the middle, continuing along the postero-dorsal slope. 
Hinge line somewhat more than one-third the length of the shell, slightly an- 
gulated between the beaks ; buccal slope slightly curved, the anal nearly 
straight; extremities obtusely rounded ; ventral margin nearly straight in the 
middle region, curved rapidly beyond. Longest dimension equidistant be¬ 
tween the beaks and venter. Pallial impression deep, without sinus (?) ; an¬ 
terior muscular pit deep on the rostral side, roundish-oval, striate radiately 
and concentrically ; equidistant between the beaks and extremity ; posterior 
muscular pit more elongate ; a feeble ridge extends from the beak along the 
inner border of each muscular pit—more perceptibly the posterior. In the 
right valve a strong triangular cardinal tooth stands just anterior to thepoin; 
1865 .] ‘ 
