§2 BULLETIN OF THE LABORATORIES 



pened upon a typical example of Cardinia concentrica. Many states 

 of preservation conceal the teeth, but in every case the foam and char- 

 acters could be exactly duplicated in specimens with the hinge so 

 broken as to reveal their casts. This species labeled by Meek Palaeon- 

 ilo concentrica, Win., indicates the prevailing opinion in Ohio as to 

 the state of the case, yet, for the present, it may be well to apply a 

 a new name devoid of ambiguity. The species ranges from the shale 

 below congl. I, to the concretionary lime-stones and sandy layers 40- 

 50 feet below. The young are short and muculiform with few teeth. 



Note. — Paloeoneilo truncata H., is the species described by Win- 

 chell as Sanguinolites marshallensis. Hall states that the interior was 

 not seen. Fig. 43, of Plate L, Pal. N. Y., Vol. V, Part II, referred 

 to P. sulcateria. Con., is probably the same, though unusually short. 



Pakieoneilo sulcateria., Con., is regarded as a synonym for P. bar- 

 risi, W. and W., Nucula hubbardi, Win., and L. nuculiformis, Stevens. 

 This we have failed to identify or have regarded as an extreme varia- 

 tion from P. elliptica. HalFs figures, stated to have been drawn 

 from Ohio specimens in part, agree wnth the last named species. 



Palaeoneilo atteniiata, H. 



(Plate IX, Fig. 25.) 



Shell very thin, nacreous; valves slightly gaping behind, com- 

 pressed, equal ; outline subrectangular, produced posteriorly, hinge- 

 line straight, extending scarcely forward of the beaks, wnth many mi- 

 nute teeth in two series, which are not in the same straight line at their 

 union under the beaks, ligament apparently external ; anterior mar- 

 gin strongly and evenly curved, extending nearly one-fourth the en- 

 tire length forward of the beaks ; lower margin very slightly convex, 

 somewhat concave at a point about one-third the length from the pos- 

 terior extremity; posterior margin acutish, the lower margin curving 

 slowly upward until by an abrupt flexture it approaches the upper or 

 hinge margin; greatest thickness about half the height, situated about 

 one-third the distance from beak to front ; a shallow depression pass- 

 ing from the slight sinus of the front margin toward but not to the 

 beaks, dorsal part of shell with an abrupt descent to hinge, forming a 

 very narrow but abrupt umbonal slope, generally also an umbonal 

 ridge nearly parallel to the hinge ; beaks small, approximate, extend- 



