172 AMERICAN JOURNAL 



rather thin and compressed, beaks very narrow and pointed, not 

 prominent. Surface covered with about thirty not very promi- 

 nent rounded ribs from which spring sharply-vaulted scales, a 

 smaller smooth rib between each pair of scaly ribs, and occa- 

 sionally separated from them by one or two raised lines. Color 

 uniform brownish red. 



Length 77, width 72 mill. 



^a6.— Bay of Muscat.— Dr. W. S.W. Ruschenberger, U.S.N. 



Remarks. — This very fine species belongs to a group em- 

 bracing P. asperrimus, Lam., P. j^riinum, Reeve, etc. ; it is dis- 

 tinguished from all of them by the pattern of its ribbing. I take 

 great pleasure in dedicating this species to the presiding officer 

 of the Conchological Section of the Academy of Natural Sciences, 

 in recognition of the intelligent zeal with which he has, through 

 a long series of years, labored to augment our collections. 



