OF CONCHOLOGY. 33 



OBSERVATIONS ON MELANTHO. 



BY JAMBS LEWIS, M. D. 



In the collection of Mr. Chas. M. Wheatley, of Phoenixville, 

 Pa,, are many very interesting and valuable specimens illustrat- 

 ing the genus Melantho to a very considerable extent. Through 

 the kindness of Mr. Wheatley I have recently been permitted to 

 examine a portion of his collection of Melantho, and the result 

 of the examination has been to lead me to a better understand- 

 ing of a few points that have until now been perplexities and 

 the cause of error. 



In conchological investigations, as well as in any other pursuit, 

 progress sometimes requires the investigator to abandon opinions 

 previously received, that others, based on more numerous and 

 significant facts may take their place. The facts and the opin- 

 ions about to be presented, as having baen derived from an ex- 

 amination of a part of Mr. Wheatley's collection, are such as in 

 some instances require the abandonment of opinions previously 

 entertained, while at the same time they help to simplify and 

 systematize the imperfectly understood literature of that portion 

 of American Conchology to which they relate. 



A few weeks since, in a letter to Mr. Geo. W. Tryon, Jr., I 

 gave a brief outline of a system of grouping which I had con- 

 ceived for the genus Melantho. 



I had regarded Melantho as embracing four well characterized 

 groups — as follows : 



First. Shell heavy or solid, more or less globular ; opercle 

 gibbous ovate or elongate. Examples : M, ponderosa, Say, 31. 

 Integra., Say, 31. regularis, Lea., 31. obesa, Lewis. 



Second. Shells a little less solid, more elongate, whorls 

 fiattened or compressed below the suture, sub-angular on the 

 middle of the last whorl ; opercle gibbous ovate. Examples : 31. 

 coarctata, Lea, 31. exilis, Anth., 31. rufa, Hald,, 31. suhsoUda, 

 Anth. 



Third. Shells of thin texture, whorls usually regularly round- 

 ed, suture well impressed, spire regular in its proportions, and, 



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