146 W. B. Dicight — Recent Explorations in the 



The concentric ridges are somewhat wavy as seen under a 

 strong magnifier; they are semi-circular; a number of those 

 lying nearest to the front margin, run out along the upper part 

 of the lateral margins ; but the remainder, and larger number 

 terminate in regular order along the cardinal border. In front 

 of the central portions of the shell, the concentric ridges, 

 which number about 12 to 15 to a millimeter, are regularly 

 concentric ; but nearer to the beak the number, and the irregu- 

 larity greatly increase. At a point about one-third the length 

 of the shell, from the beak, there are twenty-five or more to 

 the millimeter ; as the radiating plications are numerous in 

 this part, there is caused a complexity of curves, which under 

 a powerful magnifier produces the effect of elegant and delicate 

 basket work. The radiating undulations are very irregular in 

 position and number, they are not thoroughly continuous from 

 the beak, in specimens observed, but appear at irregular inter- 

 vals singly or in groups ; while apt to be crowded around the 

 beak, they are rare near the front margin. On the best speci- 

 mens, about 25 have been counted in the central parts of the 

 shell just forward of the beak ; had they extended in equal 

 distribution around it, quite to the cardinal border, there would 

 have been about 50. They are also unequal in breadth ; where 

 they are somewhat regular, the interspaces about equal the 

 plications in width ; these plications are multiplied by implan- 

 tation. / 



The following internal markings are indicated by the study 

 of a specimen (fig. 8,) which is supposed to be an umbonal 

 fragment of a ventral valve of a Kutorgina Stissingensis, from 

 the same locality. 



The original specimen is a natural impression of the interior. 

 The figure is drawn from a gutta-percha cast of the same, which 

 therefore represents accurately the interior of the valve. In 

 front of the deltidial groove, a thin medial septum extends 

 toward the front. Lying close to this septum and divided by 

 it, there is a posterior and an anterior pair of circular muscular 

 impressions, separated from each other by a broad and low trans- 

 verse ridge. Fine radiating lines extend out from along the 

 septum, the front ones making a small angle with the latter, 

 while the more posterior ones start out from the septum in a 

 lateral direction, but are soon deflected into their proper radial 

 position. 



It is not quite certain that this latter fossil is identical with 

 K. Stissingensis. It is an example of rather numerous organ- 

 isms found at this locality, which for some time I supposed to 

 be a new species of Lingulella, allied to L. ella. But as its sur- 

 face-ornamentation appears to be quite exactly that of the K. 

 Stissingensis, and for other reasons, I am now inclined to think 



