Jim,
  You can find information about Nodipecten fragosus and N. nodosus in JT
Smith, Cenozoic giant Pectinidae from California and the Tertiary
Caribbean Province.  United States Geological Survey Professional Paper
1391, dated 1991.  She lists N. fragosus as being the form from North
Carolina to the upper Caribbean region and N. nodosus as the species from
the lower Caribbean to South America.  This is also addressed in the
second of the two papers below.
 
Carole Marshall  American Conchologist 23(1):4-9   Recent Changes in the
Pectinidae Part. 1
 
C. Marshall Amer. Conch. 23(3): 4-6, 12  Recent changes in the Pectinidae
Part 2.
 
Sowerby used a different Argopecten as the type for A. circularis.
Several other names proposed were already preoccupied.  The next available
name was A. ventricosus (Sowerby 1845).  I do not have the paper that
discussed this at hand but Marshall gives a nice summary.
 
 
Charlie
******************************************************************************
Charlie Sturm, Jr
Research Associate - Section of Invertebrate Zoology
                     Carnegie Museum of Natural History, Pittsburgh, PA
Assistant Professor - Family Medicine
 
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