OF CONCirOLOGY, 



193 



These fossils, judging from very small specimens of the stra- 

 tum, were deposited on a clay bed in vast abundance, entire bi- 

 valves and univalves being mingled together among a multitude 

 of fragments. It seems clear that they were not transported 

 from a distance, but lived and died in the vicinity of the spot in 

 which they are found, and near the shore of a large river or estu- 

 ary, for the many fragments must have been washed from the shore 

 among the living specimens. Most of these fossils, many of the 

 small ones very delicnte, are as perfect as when living, some spe- 

 cimens of Neritina and Pachydon retaining the epidermis, either 

 whole or in part. When the valves of Pachydon are separated 

 the shell is found to be filled with a drab colored sandy clay, 

 holding minute scales of mica, and frequently ferruginous. 



Ciasteropoda. 

 IS^A, Conrad. 



Subulate ; spire produced, apex slightly eroded ; last whorl 

 rounded, slightly umbilicated ; aperture ovate, entire in front, 

 peritome continuous, reflexed and prominent on the columella 

 side. 



This I presume to be a fresh water genus closely allied to Tri- 

 cula, Benson. It differs only in the great prominence of the 

 inner lip, which is nearly erect, and the more acute angle of the 

 aperture. I should hardly have considered the fossil generically 

 distinct from Trieula if it had been found in India, where the 

 latter is living. 



I. Ortoni, Gabb.— pi. 10, fig. 10, 13. 



Mesalia Ortoni, Gabb, Amer. Journ. Conch, vol. 4, p. 198. 



Mr. Gabb has given a full description of this species, but his 

 specimens were not perfect enough to show the peculiar charac- 

 ter of the reflexed labium. The figure is of the natural size. 

 Fig. 10 is an enlarged outline of what is supposed to be the 

 young shell. 



I. LINTEA, Conrad. — PI. 10, fig. 6. 



Turreted, rather widely subulate ; whorls 6, regularly convex, 

 with revolving raised lines, 6 or 7 on the penultimate, and about 

 8 on the last volution, with a minute intermediate line between 

 some of the larger ones ; the last whorl obtusely rounded at 

 base ; aperture oval. 



LIRIS, Courad. 

 Elongated, subcylindrical, with convex whorls and oblique Ion- 



