VHE NAUTILUS. 185 



surface. Shell moderately inflated, beaks not very prominent, sur- 

 face white, the young nearly smooth but gradually becoming finely 

 concentrically wrinkled toward the margin and the wrinkles wavy 

 •or more or less interrupted ; lunule large, similarly sculptured, 

 bounded by an impressed line but not depressed ; there is no defined 

 escutcheon ; epidermis thin, pale, closely adherent and smooth ; 

 interior chalky white, polished; pallial sinus angular and deep; 

 margins smooth ; sockets of the hinge deep, hinge teeth normal, 

 slender; the anterior tooth small but well defined. 



Shape of the shell very nearly a true oval, the height great( st 

 about midway between the two ends ; base and ends evenly rounded. 

 Lon. of shell 67*0; alt. 49*0 diam. 32'0 ; beaks behind the anterior 

 end 20*0 mm. 



This fine species is No. 291 of my list in Bull. 37, U. S. Nat. 

 Mus., where it was referred with doubt to a fossil species which 

 proved to be of a different character. It was first collected by 

 Wurdeman during the earliest Coast Survey work on the Texan 

 coast (about 1856) and has since been sent to the National IMuseum 

 from Galveston by R. R. Gurley of the U.' S. Fish Commission and 

 later by J. H. Singley of the Texas Geological Survey. It is a 

 Dione of the section represented by D. Sayana or convexa and must, 

 when in really fine condition, be a very elegant species. 



A FEW OBSERVATIONS CONCERNING DEATH OF FRESH WATER 

 MOLLUSCA. 



BY DR. V. STERKI. 



In the last number of the Nautilus Dr. Strode repoi'ts the death 

 of Anod. corpulenta Cpr., in Thompson's Lake, 111. To his case I 

 would add a few observations of a similar nature, though not so strik- 

 ing, which may, in some way, help to elucidate the question. 



A few years ago, at exceptionally low water, I found in the 

 Tuscarawas River, numerous Unio subrotundtis Lea, dead, in their 

 natural positions, buried in the gravel, the valves slightly gaping. 

 The soft parts were in a more or less advanced state of putrefaction, 

 partly dark colored. This last fall I noticed the same phenomenon 

 in the same place; it was amidst the riverbed, around some small 

 low-water banks, in very shallow and comparatively quiet water. 



