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 C/i- 

 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 charactersvof 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 a 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 sirt- 

 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 hino-e 

 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 \'et 

 fallen under my observation. 



Conrad, in the paper referred to, has described Nuculites maclroides. 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. 



SANGTJINOLARIA, Lamarck. 



Sanguinolaria 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 rmore than one-third the length of the N shell, slightlv 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 ajong the 

 inner border of each muscular pit more perceptibly the posterior. In the 

 right valve a strong triangular cardinal tooth stands just anterior to the point 



1865.] 



