The only shells for which you can be certain of the collection data are those you collected yourself, and then only if you keep good field records and don't rely on memory. Receiving a shell from someone else who has personally collected it is reliable if that person keeps good records. But data on a shell purchased from a dealer cannot be verfied. For the most part, dealers do not personally collect most of the shells they sell. They purchase from wholesale suppliers, who for the most part likewise do not personally collect the shells they sell. Wholesalers typically purchase shells from various local collectors, fishermen, etc., some of whom may keep reliable records, many of whom do not. Some wholesalers try to keep separate data for each lot of shells they purchase. Others pool the shells of a given species, received from several suppliers. Some wholesalers, especially in the Philippines, make regular buying trips to various outlying islands, dealing with fishermen and local collectors, or with local suppliers who in turn purchase from local collectors. The chance that detailed collection data will remain with a specific shell through several changes of hands is, frankly, not good. That's why most dealers provide only fairly general locality data. Better to have accurate general data than inaccurate specific data. The above is not a criticism of the dealers in question. It's just the way it is, and it affects even the most honest and meticulous dealers. That having been said, there are of course some suppliers or dealers who will simply fabricate collection data because a specimen shell with data is worth more than a shell without data.
(Answer by M. Paul Monfils via the Forum)

I think You know the answer : if there are no data or if the data are not reliable , You just cannot know or be sure . At least if You find a cypraea englerti in a shell shop in florida You can presume it comes from somewhere on the Easter Island . Every collection has a good number of shells without or worse with wrong data . That is the real problem : shells provided with ( bona fide or MALE FIDE ) wrong data . I suspect data on some of my cernica from rare locations ( expensive )to have been manipulated , idem dito for cypraea ocellata that came from 5 " different " locations but looked suspiciously similar ( except the price who was tenfold for some of them ) .I prefer to have a nice cypraea without any data , than wrong data.
(Answer by M. PVDB via the Forum)

Sand Dollars are not really "shells" in the strict sense. The shells that most collectors collect are from a group of animals called molluscs (or mollusks), which includes clams, oysters, scallops, snails, conchs, octopus, and their relatives. Sand Dollars belong to an entirely different phylum of animals called echinoderms, which also includes sea urchins, starfishes, sea cucumbers and their relatives. A sand dollar you find on the beach may be either smooth white or slightly fuzzy brown. If it's brown, it is a fresh specimen and looks just as it did in life, and is covered with microscopic spines. If it is white the spines have fallen off after death and it has been bleached by the sun.
(Answer by M. Paul Monfils via the Forum)

I have just received the last issue of Xenophora magazine (AFC publication : http://www.xenophora.org/ .
And guess what is inside ? The explanation of thye ii mystery

When some dedicate a species to someone (human) he transforms
the name with "us". Then Two cases appears :

The name does not already finish by a "i"
====> Name = cuvier => Conus Cuvierus
Then "us" bcomes "i"================>Conus Cuvieri

The name does already finish by a "i"
====> Name = cuvieri => Conus Cuvierius
Then "ius" bcomes "ii"================>Conus Cuvierii

I hope my english is not too bad ;)
(Answer by M. Touitou David via the Forum)

That would mean that any species named for Hugh Cuming, whose last name does not end in an "i", would be spelled "cumingi", correct?

And assuming that Hyriopsis schlegeli (italics) was named for a man of German ancestry named Schlegel (sure looks and sounds to me like the German language), whose name does not end in an "i", would be spelled as typed above, correct?